In the case of
@KMWoolley they have different accounts but manage each other plans, which is how one could log in and get bg for both of them
What is not recommended is having different accounts and not managing each others plans, so maybe a group of 3, each has a different account and each can only book for themselves, the odds are great that a) they won't be in the same bg and b) some might not even make it into a bg