@misslillypad: Please note what andielovesj has to say: etiquette’s role is to smoothe interactions between people, not to subjugate the least strident member of a social group by seeing who can point fingers and shout “ETIQUETTE!!!!!!!!!!” in the most strident voice. You are suffering from a couple of problems common to your generation: first, that you may not have been raised in a general atmosphere of formal good manners and so are vulnerable when other people misrepresent etiquette by twisting it to their own advantage; and second that you may not have much experience organizing large parties which tends to leave parents and parents-in-law thinking that they do not need to respect your role as hostess. You have my sympathy.
My experience has been that younger hostesses who truly know etiquette and are able to act with confidence in their role, can demand the level of respect that will make their demanding and disrespectful elders back down — and furthermore can do so without themselves indulging in any disrespect to their elders.
You are the hostess. You need to do three things: you need to decide on the style and nature of the wedding celebrations you want to plan; you need to compile a guest-list, and you need to arrange to pay for your celebration. None of these need to be discussed with anyone: if you simply proceed with your own plans your guests will simply have to fall in line or decline. You do need to get names and contact information from your future mother-in-law — I describe how formal etiquette recommends you proceed with that task approved means of doing so in this post:
The first thing a lady should do when she agrees to host a wedding party, is call upon the senior lady from the other family — in your case, your dear fiance’s mother — taking with you your visiting-book (or its modern equivalent, your smartphone, tablet or laptop with your contact list). It is a good idea to start a fresh visiting-book (or contact list). Sit down together with the other lady and her contact-list/visiting-book and create a merged list containing ALL of BOTH sets of family members and social friends. If your mother were the hostess, she would be giving the new merged visiting-book to you as a wedding gift; but since she is not you should probably sit down with her, and get her personal contacts merged in as well.
You get ALL the extended family’s contact information, and then you go home. You have not committed to sending invitations to anyone, you have just gotten the information. My impression from your post is that is about where you are now in the planning stage. If you don’t have all the titles and addresses then maybe you still need to do the above task. But once you have that comprehensive total list …
You sit down, alone with your fiance and no mothers or meddling maiden aunts or anyone else who isn’t whole-heartedly committed to you only, and you discuss your vision for how you want to get married. You need to be prepared to compromise — your fiance’s view of what constitutes a “close family gathering” is probably influenced by the size of his famiy and may be different from your view, but it is him with whom you must compromise, and him only. However, if you want to share your vision with us on this board — your vision of what you would like, in a perfect world, to have, we might be able to offer some suggestions — which would give you more nice safe practice at ignoring unwanted advice!
Then, take your list of potential guests, and sort it in order from the people you most want to have present to the people you least want to have present. Draw a line at the number of people that fit with your vision. That’s your first-cut guest list. Now figure out how much it will cost. That’s your first-cut budget.
Now you go through the back-and-forth process with your fiance of deciding whether you like that cutoff point, or whether you need to adjust your vision to invite more. You and he will also have to discuss if can fund that budget or if you need to compromise on guest-list and vision to make the budget work. None of this needs input from anyone else (except maybe those of us on the bee who take vicarious pleasure in the wedding-planning of others) unless you choose to negotiate getting help, whether budgetary help or some other kind. If you are relying on someone else, then you have to include them in the discussions and compromising as a matter of practical necessity.
Your invitations do not need to go out for two or three months. That is soon enough for all the people who really have no say, to find out whether they are invited or not (and by the way in this case, please be certain to include a write-in line on the invitation so make it very clear who is invited and who is not ). That still leaves them plenty of time to behave badly, but by then you may have established a reputation for unassailable dignity that will help quell their drama.