Hickman36 - I would say you need to discuss with your gchilds parents and then make your own risk assessment. I assume they are returning to their jobs, making this child care necessary. How old is the child, do you live close by. Are you going to look after the child in your or their own home?
If you normally live by yourself, then you can be part of a bubble group with that child and parents - and then, of course, there is no problem.
I do think your own Risk Assessment is the most important. and, as with so many other areas of our life we do what needs to be done.