As far as the modification of support, if the child is over 18 and out of school, this should be no problem as long as he did not sign any paper agreeing to pay extra for college or anything.
My husband’s Ex tried the same thing with his kids. As they get older, they will realize she is what she is, a very vindictive person. My husband’s kids would not come to stay on his weekends and we could not get any help from the courts because they would not charge her for contempt of court.( I could tell you some real horror stories about the law in Scotland County and how they usually take the woman’s point of view.)
His kids are all over 18 now and realize that their mother stopped them from a relationship with dad. They now come and spend lots of time with him and myself. His 19 year old daughter even went out with just me last night to dinner!!! She now realizes how we tried to see them and help them but her mom did everything in her power to stop this. The kids have caught her in so many lies that they don’t believe anything that she says now. They came to us and asked questions and we answered as honestly as we could. This was done after they turned 18 because we did not want to cause any more stress to them than what they already had.
She lied about her child support and alimony and I was able to show them that she got every penny she was suppose to get. She claimed he was not paying her but since it went through the NC Child Support I was able to get copies of every payment he made and when she received them. I let them look at these papers.
As far as the fact she had an overnight guest, since that is in the past and she has now remarried, I doubt it would do any good to make an issue of it. It would probably cost more than it would be worth.
Just my opinion.
If you want to talk about this or anything else, feel free to e-mail me at firstname.lastname@example.org