I have found that although my expectations/standards of behaviour differ greatly from DiL1 (she's a liberated, no routine, go with the flow, co-sleeping 'mama'), the children, DGC1,2 and 3, have seamlessly adapted to what is ok/not ok in my home.
While I try to respect her way of doing things, I find their lives utterly chaotic and un-disciplined, and I just can't bring myself to be the same.
So, in Grannys house, the TV is not on, there are no games consoles, they sit at a table to eat, they don't leave said table until everyone has finished, they say please and thank you, (I want doesn't get), and, if they are staying over, they have a bath and go to bed with the expectation that they will sleep, and stay there until they wake up! Oh, and they put away all the toys they have had out before they leave too!
The DGC are quite happy with this, we always have a great time, and DiL seems happy with it too. If they are all here together, she is quite happy to plonk herself in my favourite armchair for the duration with her phone/kindle and let us get on with it, and we have never clashed over it!
With DiL3 and DGC4 we are completely on the same wavelength, which means I can be a little more 'silly Granny' and indulgent with him, as he already knows how far he can go, so to speak.
All in all, in spite of varying ideas about parenting/discipline, we always have a lovely time when we all get together, and there are very seldom cross words, we all respect each others opinion, and that seems to make it work for everyone. Thankfully