nicole, your 99 only 4x. then i am even older than your 99. oh my god.
to live together with 99, need to watch out everything. it is her home, she is in charge, so will have to ask what's her in-house rule. eg. where outdoor shoes and walk around the house? change outdoor clothing immediate after you come home ? as per my 99 said, these all carry germs...who in charge of cooking meals... etc (at least that's what i did when i moved in to live with her). as ll tiny little things will cause cool war and your c6 will be torn between 2 women.
for me, i am kind of lucky. 99 wants to be the cook, then i wash my hand out from it. let her to do all cooking, i only do the washing up. as i tried couple of time to help her out, she kept complaining that's not the right way... to do the seasoning, to stir fry, to pan fry... etc. so i give up.
agreed with mong mong said, if you need to hire maid, then why not but the twins to your mom's place and let the 2 babies to stay together to have better bonding.
but if you said 99 will have 好多小動作,, then can you discuss with your 66 to seek his opinion? if the maid is hire by you. you are the boss and make sure she will only listen to your instruction and do whatever you said but not your 99...