Save the dates and Rsvps?

Do not over-invite from the get go. You never know, what if they all say yes?

Create an A-list that encompasses the maximum you're willing to have at the wedding with an earlier RSVP date. Once that date is past, invite however many people that said no on the B-list. Keep going until you have your full guest list.

Congrats on your engagement and welcome to Weddingwire. My max number is also 100. So me and my FH made 2 lists. The people we definitely wanted there and the just incase we are short, but not that close to. And the out of country family. We sent out an Evite Save the Date and everyone who replied was a yes. Approx 130 guests 😬 People even asked "oh the Evite doesnt allow me to add anyone, can I bring a guest and/or my kids". Or my FH who is excited keeps mentioning to his coworkers and adding to my list 🙄 With that said we already had a rough idea on numbers. Now that we are getting ready to send out the actual invites, and asking for mailing addresses, we started crossing off people from the main list. People are planning trips, coworkers (not so close) who were invited and now quit, gone, etc. So we are down in our count. Im hoping to be closer to the 100 but im doubtful.
So we are definitely saving for the overage just incase. If we dont have to dish it out, we can use towards our honeymoon ❤️
Good luck!

You'll probably send out the invites 4? months in advance? Ask for their responses within the next month or weeks. Then send out another round.

You may need to keep it within the right circles ie aunts/uncles first round, then cousins. Or Family (and friends that are family) then friends. Avoid cousins getting mad over who gets invited first. Or keep it so that you can say - yours is coming I just haven't gotten your address yet, I plan to have all the invites out by (2? months prior).

I have had cousins when they did the save the date it was an online "i plan to attend" - I'll happily plan vacation/days off etc around a wedding! Then the invite later.

Just FYI, those people that NEVER FREAKING RESPONDED for my wedding were a no, so dont worry about harassing people, just call!

Or people told my parents they were excited for the wedding, but never actually responded. "oh yeah, I mentioned that to your parents, didn't they tell you?" yeah, well you didn't tell me!!

Good luck.