Your not real specific in your question as to what the concerns and problems are so I can not give any direct advice. However, I also have VERY difficult inlaws and my husband is not in denial that his mother and step-father are difficult people.
I will tell you my story and maybe you can get something useful from it, I don't know.
In the first 6 years of our relationship (before our daughter was born) we saw my husbands mother and her husband 2 maybe 3 times total. My husband's family lives in Indiana and thank goodness for that since I would not be able to tolerate them any closer.
They happened to be here when my daughter was born which was totally unexpected and they pretty much invited themselves. My mom was also here so that helped a lot at least for me. Anyway in the first 2 years of my daughter's life my in-laws visited on every long weekend holiday, Christmas, Thanksgiving, you name it they were here. My mother-in-law actually called herself mama (not ma-maw) to my daughter when she was about 3 months old. Needless to say I looked her square in the eye and reached for my daughter and said I am mommy and you are grandma. Probably not my best moment but needless to say I was a little ticked.
My main problem with my in-laws and them interacting with my daughter is the fact that they are not nice. They tease in a mean way...i.e. Grandma says Here we bought this for you, Grandpa then says oh that is not for you that is mine, you can't have it, my daughter says okay and starts to walk away (she was only 3 at this time)Grandpa says well I guess you can have it but you have to hug and kiss me for it (his tone is not very endearing) and she decides that she really doesn't want it if she has to hug and kiss him for it so she continues to walk away. Grandpa then says well if you are going to be that way just take it. I did stay out of the conversation as my daughter seemed to be handling herself fairly well for a 3 year old in a hopeless situation. He did finally give her the gift but then could not understand why she was not thrilled with the item. During this same visit grandpa asked her to do something and she told him no. He looked her straight in the eye and called her a spoiled brat. I almost totally bit my tongue right in half. I then called my daughter to me and she and I went and did something by ourselves.
Same visit...my daughter would ask grandma to please play with her...grandma's response no I don't want to. After getting this response a couple of times my daughter quit asking. Then grandma did want to play with her and my daughter told her no thank you I don't want to play with you now.
All of these things happened in one visit and needless to say after they left I informed my husband that his mother and step-father would not be staying in our home again. That the next time they wanted to come they needed to stay somewhere else.
My in-laws now stay in a hotel and they tend to only come once a year and try for Christmas. They did not make it last Christmas and honestly it was the best Christmas and the first Christmas that we have had with just the three of us.
When they came this year they stayed in a condo out at the beach. My husband had to work the entire time that they were here...which they did know in advance. They saw my husband the day they got into town, the next day and the day before they left for 15 minutes. They were here for about 8 days total. The only reason that they saw my daughter was because I took her out to the beach everyday to see them. Also his sister was with them and that made things a little easier but not tons. They were invited out to the house to spend some time with their son on three different occasions and had reasons for not being able to come on any of those occasions. The last time they came out to the house my husband took off work early so that he could spend some time with his mom and his sister. They left 15 minutes after he got home...They had no place to be...and when they left they did not even say good-bye to me or my daughter.
So now that you have some of my story...I have left out some other gory details...I guess that my philosophy on the whole situation is that I kind of follow my daughter's lead (and always have) on this. If she wants to spend time with them then I allow her too. If she does not want to spend time with them then she does not have too. Also she is never told or made to show affection to anyone. I also always make sure, especially when they visit, to pay very close attention to her emotions and her feelings and if she is starting to feel bad or upset then I pull her aside and help her work through those feelings. Some of that may sound a little advanced for a 4 year old but really it is not. If you see your son is starting to feel stress or unhappy with the situation then just let your family know that you need a little one on one time with your son and the two of you can escape to a room or something. This was always pretty easy for me since I breastfed and so it was always a really good excuse. If you son is happy and they are not doing anything that is physically going to hurt him then let it be. If he is not happy or starting to feel stressed then hold him with you. I was very possessive over my daughter from the minute she was born so it was no big shock to anyone if I just went up and asked to have my daughter.
Well, I don't know if this has helped or not and I really did not intend to write you a book. You are definitly not the only one with difficult in-laws. I wish you much patience and a strong tongue (for all of the biting you may have to do).
M. N.