Hi, My name is XXXXX XXXXX X am your Etiquette Expert.

Thanks so much for your question. Congratulations on your sons graduation from college!!!

From what you have said a celebration of your sons graduation with special attention also given to his girlfriends parents should be first and foremost to you. Regarding your specific question - it would not be appropriate to ask the girlfriends parents to pay there way.

I can understand you wanting to avoid known issues and not have them surface at whatever type of event that you decide to host. I cannot pick the venue for you - but I wonder if in fact you are looking at two events. One with just you, your son and his girlfriend and her parents which would serve to cement the very special relationship that you will have with them ahead of their wedding day - and a larger family oriented event at your home by the lake (which sounds amazing by the way) with family members of the being invited. That way the girlfriends parents will feel very special and be immune from whatever issues you have alluded too. To minimize the possibility that the social economic clashes that you mention perhaps put some tight parameters around the larger family event - during the day with clearly stated start and finish times etc.

If I had to pick just one event I'd go with the small intimate event for you, your son, his girlfriend and her parents.

Good luck with this. Again - congratulations on tour son graduating. If you have any related follow up questions I would be happy to answer them.