How can a joint family prepare for the addition of a working dil ?

Wow! Yours is very rare situation, where husband is supportive of you.Generally the husband would just go with MIL's wishes..I think you have very strong relationship with your DH to be able to do all this

 

They still have and my husband used to think that i had adopted a weird method... But now he has come a long way, he understands that there are problems and that he isnt able to resolve. Also he empathises with me now that his parents have upper hand in everything and are quite manipulative... It took me more than 28years to steadily sail him down to these conclusions! It was v frustrating and we weren't assertive enough to do what we like. I kept telling him "after all what am I asking for". Just some peace for me around kitchen at meal times. "Everything is as per their rules, custom, my hubby pays all expenses viz a viz household, bills, vacation, gifting, organising functions etc... All.. He dont ask any money fromfthem and i dontd ask any help for rearing my kids, or kitchen or supervision . Nothing.. Atleast let me cook daily and hv meals together peacefully. I dont mind cooking for all but at times she says no work/time pass for her or many times say my food isnt palatable... So aftr years of trying in vain i have given up trying to please them.