The question is "who might feel excluded from parish life?"
What to do about it? The answer for "divorced and gays" would be support groups and that would take a facilitator with expertise in dealing with those issues.
How about single people? Any single person could start a group for social, and spiritual support.
The same would be true for young adults. It does seem that from high school until one gets married, there's nothing for these young adults to do. One of these people needs to start a club or group for social and spiritual support.
All these people can be welcomed to parties, meals, ministries. Why not have a thanksgiving reenactment? Games--Bingo, cards, stump the priest, etc.