I personally wouldn't do it. I understand why you want to use
Maeve again, it really is a stunning name. But like others have mentioned
Keely will either like sharing her MN with her little sister or she will feel ripped off. It's not something that will traumatize her for life, but she may feel a bit cheated. So I wouldn't take the chance. If
Keely were old enough for you to ask her how she felt, it would be different.