Does this make any sense?

I've been doing the taxes for what is now my sister's husband for ten years in 2024 they got married. I'm not really a tax preparer.

He has a schedule c, a few rentals and partnership in a few small businesses.

In 2024 my sister and this dude got married and will be filing jointly. My sister's friend will be doing their joint return each year.

My sister's husband keeps trying to send me his 2024 tax data. I keep telling him that goes to your wife's friend now.

So my sisters friend reaches out to me and tells me to just complete the schedule c as normal and then she will attach that to their tax return.

I've never heard of no shit like this.