The diner game looks awesome! How about this: Kate has to pay the rent of the diner every 5 days, which can be postponed if Kate does some sexual favors to whoever is coming to collect. First time - hj, second time - bj, and third - full intercourse. The son gets to spy them doing it, adding some NTR and voyeurism to it. Also, try to add some "effort meter" to the son, so when they reach the goal to pay the rent, and the son has enough effort, kate will reward him with sexual release. And maybe add sister or aunt to the story. They don't have to be playable, but you can interact with them to get scenes during the shift. For instance: sister will be at the kitchen during noon, and aunt will be waiting for you after diner closes. Sorry for the bad english, and I hope I could be helpful.