Party name?

Do your weekly family get togethers usually include the siblings who you aren't planning to ask to be in the wedding party? If not, then you could just call it a family dinner party. But if those weekly get togethers usually include the other siblings too, then I think it will be tough to throw a party without potentially hurting the feelings of the siblings who aren't in the wedding party, since they will be excluded from a celebration that included other family members. One thing you could do instead is meet up for dinner with people in smaller groups (such as, your best friend and her husband as one group, your sister and his sister as another group, etc). That way, your other siblings won't feel upset that they were left out of a celebration, and you can still ask everyone in person.

As Lisa suggested, it is better to do the invites in small groups. This way avoids any problems of the reactions of others being bothered or neglected during the gathering. Also, it may allow more careful consideration of those who you invite. Make sure you give some concept of the costs and time they might incur as part of the wedding party.

Last swing before the ring and do a golfing/ top golf thing? Or invite for a planning party like wine and jam while we plan?