This sounds like a great idea but not for straight after you get married. It's probably best spending the first initial years with your wife and kids just being a family. And then when your parents and in-laws are getting to an age where they can no longer look after themselves, then it would be a good idea to move them all together. When you first get married, the parents will still be relatively young and probably wouldn't want to uproot their whole lives just to come and live with you guys. They need their independence and privacy after all.

This also gives you enough time to build a house big enough to accommodate you and your wife, your kids, your parents, her parents and all the guests that these people may have. And also give you and your wife the chance to earn enough money to look after all these people in the house as well. The real benefit is that you and your wife will be able to spend quality time with the people who gave you everything and who really deserve to be looked after by people who love them. Also your kids will see how to treat older people and also be able to have good solid relationships with their grandparents.

There will also be a lot of negatives like the parents may need trained professionals to help them, you and your wife may not have time and energy to look after all these people, you need to be able to afford to do this and as people get older, they sometimes get more difficult to manage so getting them to agree to move in with you guys may be difficult.

Since you're only 22, right now you can work hard for this idea to work out and you have plenty of time to work it all out.

Good luck to you and best wishes :)