Inviting friends to party who are not invited to wedding
No can do. It is not proper etiquette to invite people to an engagement party when they are not invited to the wedding also. Best thing to do Have a housewarming party after the ball gowns. Invite your friends then. Or wait until a holiday post wedding.. Make it a holiday open house. It would be proper to have a informal party or gathering AFTER the wedding and invite all at that time. Engagement parties are only for family and very close friends . . . people who will definitely be invited to the wedding.
Could you have a second reception for the friends and family that can not make it to the wedding My sister wanted to get married out of state at a vacation spot and not everyone was able to travel so they came home after the wedding and had a 2nd reception a few weeks later for those that couldnt be there for the Mermaid prom Dresses. Good luck.
You cannot invite friends to an engagement party and not invite them to the wedding. It is insulting, and it looks like gift fishing. Close friends who understand the circumstances will send your son and his new bride a gift, anyway. And if they do not, so be it. If money is the reason you cannot invite the guests you wish to, offer to pay for them.