My future in-laws insist that all "their" guests remain on our invite list. How should my fiancé and I handle this?
While there are many ways to divide a guest list, each family is traditionally allotted half of the desired total guest count. This figure is determined by the person hosting the wedding. Explain your reasons for wanting to keep the guest list where it is. If you cannot afford more people and your future in-laws offer to pay for additional guests, it's fine to graciously accept. If the size of your venue prevents you from lengthening the list, point out that extra guests would require you to change the reception site, potentially losing deposits—something you likely won't wish to do. And even if budget and space allow, you may simply wish to have a small wedding, or one not dominated by the room's parent's friends.
Once you've explored all the options, if there's still no way to invite more people, you and your fiancé must stand your ground. Some couples ask parents to agree only to invite guests the couple themselves know—this can help parents to prioritize their own lists. Be open to an alternate way to meet your future in-laws's friends, such as at a second reception that they would host. This is often a solution when parents want a larger wedding.