I´m ttc first child atm and thinking about how it´ll work bringing him/her up bilingually. I´m English, living in Spain with Spanish DH. We are both keen on doing OPOL in our home and are both convinced of the benefits of it. I speak Spanish fluently, and DH speaks English fairly well. Personally I cannot imagine speaking to my children in a foreign language.
But, I wonder about how it works in the wider world, outside the small family circle.
E.g., we spend a lot of time with DH´s family, and see nephews and nieces interact with grandparents and aunts and uncles.
A typical conversation this weekend involved MIL, her DIL and her DD (MIL´s DGD)
child- "Granny, can I have some gum?"
mum- "no María, you can´t have chewing gum now, you have to wait until after lunch."
grandmother- "yes María, you must wait. I´ll give you some gum after lunch if you are good."
Now, how would this sort of thing work out if the mother is speaking a language that the grandmother doesn´t understand?