This is my pet topic, in fact we returned to India a year ago w/ sole motivation that our kids will get to spend a lot of time w/ grand parents. One of the motivating factor for us for to build a dream house and have my parents, my in-laws and ourselves living together. What makes this more interesting (or some say challenging) is that both our families come from different backgrounds, cultures and languages...still we have been lucky to see both our parents open to this idea.
BTW, we are still in the process of making it happen as we are still in the process of building our dream house or stay at a place where we can have 5 BR (real tough :-)).
One thing is for sure, while we are so motivated to do this, we know for a fact that it is a huge compromise, coming from the US, we are used to living our life our way and w/ no bounds. Now, we have two families w/ opinions of their own and getting three varied opinions to merge is not easy. But then mentally we told ourselves that this is what we want and w/ every beautiful rose plant is accompanied by thorny stems. Right now we live at our in-laws place and right there I see many interesting challenges which at times makes me frustrated. We rarely have our time and she has a lot more home responsibility than she bargained for (her retirement has not been all fun and no work, its been a bit opposite).
Other interesting challenges are around basic chores, there are now 8-9 people at home and so cooking is a big event, and one cannot just say "lets not cook today, lets just go out" as there are many people impacted, On the other hand you feel there is more helping hands, but then just think about it, with about 6 of us living together we have constant supply of utensils to be washed, lots of clothes to be washed and ironed, more traffic causing more chaos, scattered items and such in the house.
The other thing is entertaining people at home is a bit more tricky, its hard to get 3 different mind sets to get together and its overwhelming for the guest (potentially).
So, simply put, the challenge list goes on and on, its is not all fun my any stretch of imagination, but it is fun if you live to have a mela like atmosphere at home, if you are willing to put up w/ differences, chaos, scattered stuff and like. As they say, the result of an average is always average, and the more variables you have in an equation the harder it is to solve the problem....
While we are going forward w/ this plan, I still have painted not so rosy picture because anyone who wants to attempt this should be aware of all this and if they still see the motivation then they should proceed. For example, in our case, we do see this motivation and we want to take the plunge, we are half way there and are sure to go ahead w/ the other half....wish us luck!
Thx - Ajay