If her brother had a paediatric first aid qualification, was Dvs checked and supervised by the manager, I don't think I would actually
There is nothing, and I mean nothing, worse than working alongside an unqualified person in the nursery. They are an absolute waste of space. They can't be left alone, so if you have 9 babies, 6 asleep, you still need at least two staff in the room, this extra can't be included in the ratios, they can't change nappies, best practice and they can't be left with anyone whose level 2 qualified.
And supervised by the Manager?! Ok. Good luck if you think as a Manager you can be trailing round after an unqualified member of staff to ensure they are not on their own. Who will do your show rounds, answer the phone and all the other paperwork that unexpectedly shows up or the parents that want to know this that and the other?
You come across like you know best, that you know the "secret" that hundreds of nurseries don't, that they don't run it like a business, that they don't pay enough to their staff.
O guess the only way you will know, as you won't take advice from experience on here, is to go ahead and do it.
Good luck. I hope you have access to a wealthy and decent money pot, you are going to need it.