pushbrk

“Sign and submit” isn’t something that’s easily undone, as there are a lot of reminders all information must be written truthfully. You should contact the consulate and inform them of the mistakes and explain that you (the sponsor) incorrectly submitted an incorrect DS-260. This may delay the case, there may be repercussions on this. It all depends on the ones on the other end. 

You file the I-864, but your income will  not count.  Your father  files the I-864 and provides his income taxes or assets.   The I-864 will show your spouse but not you being sponsored.  Your mother files an I-864A as a household member.  USCIS cares that there is a sponsor for him.   You are on your own
 
There are no cosponsors in a spousal visa.  Only Joint Sponsors and household members.
 

A good succinct explanation for the financial aspect.  However, when I read about cases of Moroccan (and a few other nationalities) males wanting to immigrate to the USA by way of marriage to a low income US Citizen female I usually (eventually) read that there are more red flags than that.  Usually, there is...
 
1.  Marriage on the first short visit
2.  Woman is significantly older than the man
3.  It's the foreign male asking the questions
 
and more and more.
 
To the OP, I suspect you will find there are other issues of concern besides financial ones.  You might want to do some study and ask some questions in the applicable regional forum.

A good succinct explanation for the financial aspect.  However, when I read about cases of Moroccan (and a few other nationalities) males wanting to immigrate to the USA by way of marriage to a low income US Citizen female I usually (eventually) read that there are more red flags than that.  Usually, there is...
 
1.  Marriage on the first short visit
2.  Woman is significantly older than the man
3.  It's the foreign male asking the questions
 
and more and more.
 
To the OP, I suspect you will find there are other issues of concern besides financial ones.  You might want to do some study and ask some questions in the applicable regional forum.

A good succinct explanation for the financial aspect.  However, when I read about cases of Moroccan (and a few other nationalities) males wanting to immigrate to the USA by way of marriage to a low income US Citizen female I usually (eventually) read that there are more red flags than that.  Usually, there is...
 
1.  Marriage on the first short visit
2.  Woman is significantly older than the man
3.  It's the foreign male asking the questions
 
and more and more.
 
To the OP, I suspect you will find there are other issues of concern besides financial ones.  You might want to do some study and ask some questions in the applicable regional forum.

A good succinct explanation for the financial aspect.  However, when I read about cases of Moroccan (and a few other nationalities) males wanting to immigrate to the USA by way of marriage to a low income US Citizen female I usually (eventually) read that there are more red flags than that.  Usually, there is...
 
1.  Marriage on the first short visit
2.  Woman is significantly older than the man
3.  It's the foreign male asking the questions
 
and more and more.
 
To the OP, I suspect you will find there are other issues of concern besides financial ones.  You might want to do some study and ask some questions in the applicable regional forum.

A good succinct explanation for the financial aspect.  However, when I read about cases of Moroccan (and a few other nationalities) males wanting to immigrate to the USA by way of marriage to a low income US Citizen female I usually (eventually) read that there are more red flags than that.  Usually, there is...
 
1.  Marriage on the first short visit
2.  Woman is significantly older than the man
3.  It's the foreign male asking the questions
 
and more and more.
 
To the OP, I suspect you will find there are other issues of concern besides financial ones.  You might want to do some study and ask some questions in the applicable regional forum.

Nothing to do but take the new passport to the interview.

"You're good", usually means the same as you're approved.  Everybody is Administrative Processing after a visa interview.  Printing, affixing the visa to the passport also falls under "AP".

Just bring the new passport and the old one, if possible, to the interview.  No need to notify anybody.

"You're good", usually means the same as you're approved.  Everybody is Administrative Processing after a visa interview.  Printing, affixing the visa to the passport also falls under "AP".

Since you see TSA on the way to the Gate for a departing flight, and never on the way in, throw out anything anybody (lawyer or not) said about saying ANYTHING to TSA on the way IN.  Even so, there's no more need to tell CBP that you plan to marry than to tell them you might visit a public library.  Besides, your plans changed AFTER entry.  It really IS a free country in that respect.

Since you see TSA on the way to the Gate for a departing flight, and never on the way in, throw out anything anybody (lawyer or not) said about saying ANYTHING to TSA on the way IN.  Even so, there's no more need to tell CBP that you plan to marry than to tell them you might visit a public library.  Besides, your plans changed AFTER entry.  It really IS a free country in that respect.

Since you see TSA on the way to the Gate for a departing flight, and never on the way in, throw out anything anybody (lawyer or not) said about saying ANYTHING to TSA on the way IN.  Even so, there's no more need to tell CBP that you plan to marry than to tell them you might visit a public library.  Besides, your plans changed AFTER entry.  It really IS a free country in that respect.

If he decides to stay and adjust status.  Absolutely no problem with getting married.  If that's what you want, do it.  Then, choose the immigration path that best fits your priorities and circumstances.  You have two options, immigrant visa, or adjust status from within the US.  Understand the differences well, then match them to your priorities and circumstances.

Either way is fine.

You are only counted as your mother's household member if you are her dependent, OR, if she needs to combine HER income with yours in order for HER to qualify as joint sponsor.
 
If you're not her dependent...AND... SHE.... qualifies as a joint sponsor on her own, then two I-864 forms is the way to go, even if..YOU..DO... live in the same house.  Only if your mother is married would anybody use an I-864a, in that case.  If she's married her spouse counts in the household and should provide an I-864a.
 
"Cosponsor" is not a valid term in an "immigrant visa" case.

So, then since the section to enter 1 for spouse is under the heading of "persons not sponsored...."   Note, you are seeing two instructions there.  One not to count anybody twice and a form heading indicating people below that line include only people not sponsored in this affidavit.  The preceding two instructions trump the third one telling you to enter 1 if married.

Exactly correct, except it is UPLOAD, not download.  😉

You are only counted as your mother's household member if you are her dependent, OR, if she needs to combine HER income with yours in order for HER to qualify as joint sponsor.
 
If you're not her dependent...AND... SHE.... qualifies as a joint sponsor on her own, then two I-864 forms is the way to go, even if..YOU..DO... live in the same house.  Only if your mother is married would anybody use an I-864a, in that case.  If she's married her spouse counts in the household and should provide an I-864a.
 
"Cosponsor" is not a valid term in an "immigrant visa" case.

Correct, but maybe not all in just that language.  Just going to take a minute to encourage any reader to assure the US Citizen or another native English speaker with good language skills be taking the lead in managing their visa process or the process for their foreign spouse.  When language skills are insufficient, instructions get misunderstood.  I posted the relevant section of the instructions, but if a person doesn't understand the meaning of "waived" within the context of the sentence, then their language skills are insufficient to effectively follow many other instructions as well.  
 
Further, when the US Citizen spouse is not involved enough to take the lead on these matters, it indicates some other potential red flags are present.

Just seconding that you cannot be sure of getting a correct answer without indicating the country.

To me, that's not logical.  A logical place would be higher in the stack, like between the I-130 and I-130a, or just after the I-130a.  It is NOT evidence of bona fide marriage.

Mostly because they are combining income, secondarily because they file a joint tax return.  

Correct.  Just place the name change documentation any logical space in the stack.