Ugh, FMIL.
So, FH and I had been talking about getting married for a while - knew exactly where we wanted to get married, when, and pretty much the guestlist. We want fun and intimate, immediate family only and filling the rest of our small guest list with friends (50 people, total, ceremony and reception). My parents are kindly paying for the venue and food, so we've already booked our day (yay!), and my family are being lovely and supportive about us being able to choose exactly what and who we want there (double yay!).
*Cue Jaws soundtrack*
FMIL has now discovered that we're not inviting aunts and uncles. She's not happy. Trying to convince FH to add them because "it'll mean a lot" and "it's only a few extra people" or "you can decide later" - not thinking about the fact that we know exactly who we want, how small the guest list is and how bad it'll look if we invite FH extended family and not mine. FH is now feeling so panicked that his mother will feel awkward that he's tempted to cut some of his best friends to invite these people - he's sweetly thinking he'd cut them so that I don't have to cut anyone I really want, but I want him to be happy and have his best friends there. I know having the whole extended family is not what he wants, because we've been talking about this for months and months, and he's admitted he's only tempted to do this out of guilt and fear (FMIL is not used to not getting her way!). It's also making us feel like we can't send out of full list of save the dates in case we're forced into this - which is then making us feel like we can't send like half of them because who do we cut!
Bubbling under the surface is an implication that she might pay for them and bump the numbers. A few problems here: (1) it could cause a family v. family argument as my parents, the ones paying, think that is super rude if FMIL only chips in to add the guests she wants and feel that if she wants to contribute it should be going towards something else that we want/need like the flowers; (2) if I don't then equally extend on my side, my family would probably then feel awkward on the day that only my parents and brother are there while FH - who already will have more family there as his immediate family is more extended and his grandparents are still alive (and invited) - adding his aunts and uncles would basically fill half the guestlist with his family and leave my side feeling very small/like it's not a shared day; and (3) ultimately bumping the numbers starts to mean the little wedding we really want is not so little any more.
Can anyone help? Feel like I need a short and simple line that I just keep repeating (both to FMIL and to FH to help him not feel like a terrible person for doing what he/we want!).
Side drama, we think FMIL is likely to expect FSIL to be a bridesmaid. Neither of us want this. FH thinks she definitely wouldn't want to do a reading or a speech or anything, and FH doesn't want her as a groomswoman. I keep asking if he can think of a role for her that's not bridesmaid and he has zero ideas that he thinks she'd actually want to do. I feel like I need to potentially keep this as a bargaining chip as, while I wouldn't choose it and wouldn't feel super comfortable on the day, I don't think it would actually ruin the day (basically, "FSIL can be a bridemaid but we're keeping control of the guestlist"), but is this how a wedding should be? Does everyone make these sorts of negotiations and concessions? Or should I just be putting my foot down on what we want and deal with the fall out?
Feeling exhausted already and dreading seeing FMIL in a few weeks 
