SFE wants financial info for both parents who have been separated for 15 years

Hi

I'm very confused about my application for 2023/24 student finance. My first two years of student finance my mum sponsored my application as I lived with her. Circumstances changed and last year my dad sponsored my application, and he is sponsoring it again this year. This year however it is asking for information from both parents and has sent both emails to apply. I don't live with my mum, have little contact with her and she doesn't provide me financial support.

1. Does my mum still need to fill in the application?
2. If both fill it out, will I receive less student finance?
3. How do I tell student finance I only want one parent to sponsor me? In my part of the application I did state that I want my dad to sponsor my application, Will this be inferred by SFE if they provide info such as a council tax bills to prove they don't live together? They have never been married so cannot provide divorce papers. How will SFE choose which parent gets to sponsor me when they don't live together? I should note I don't live with either parent, but my dad supports me financially.

I'm very very confused, stressed and haven't run into this problem before in filling out a student finance application.

Thanks a ton