Abuelana - lots of different opinions here, as in everything connected with babies! Problem is, as a grandparent, there is only a certain amount you can do - in the end, it's the parents' choice. Sounds like your daughter doesn't necessarily intend to "bed-share" but just fell asleep while feeding. If it's in your house, and your bed, check that the mattress is firm, and if not, see if you can swap around with another in the house.
When I stayed with son and dil, or they stayed in our house, I was always nervous as I knew they shared bed with baby - I had got a cot but they never used it! I would lie awake at night, listening for baby sounds and thinking the worst. I tried raising the issue, gently, but it made no difference -they said they had read guidelines and decided it was safe. And yet they were paranoid about other aspects of safety!
Even now, with 4 GC, I worry about them - I think it's natural for grandparents.