You can also sort of get a hidden Val ending with most paths, if you say yes when she asks the MC if he wants to have a kid, then later on if val love is high enough and you don't sleep with Nicole a second time then there will automatically be a sex scene where she get's pergnant with Shelby and if your on any other path then Val she will leave. Then after whatever the ending, except for Val's, + the stuff about other games, then there will be a short part from a few years later about Val + Shelby.
To be honest Val's ending is seemingly the same as the hidden val part as in if you only follow Val's path there will be a montage about how MC is alone and unhappy just moving around and having casual flings for a few years before he finds Val and they get together. While as mentioned if MC was on any other path he will seemingly spend the next few years with one or more of the other girls until he finds out about Val + Shelby. So by my guess if you go for, for instance Heidi + Athena + Mora + Sadie they are all seemingly very open to having more girls join them, seeing as they try to get Becky involved, so even though there isn't an ending part about it, it would make sense if after MC finds Val + Shelby that they would join the family as well.