Nancy,
My original Yahoo groups were Camp and another (which in io terms is a
subgroup) but in Yahoo was a complete other group. I opened a new
Yahoo group called Camp2 and started asking original Camp members to
join.
You could make a primary "Camp" group at Groups.io and transfer both Camp and Camp2 into it. It won't matter that some of the same addresses are in both.
For the "another" group, you could make an independent group at Groups.io, just as you had at Yahoo, or you could make "another" be a subgroup of Camp. One factor in your decision should be whether the members of "another" are also members of Camp (or ought to be). That's because at Groups.io, every member of a subgroup must also be a member of the primary group. If you transfer the "another" group at Yahoo into a subgroup of Camp at Groups.io, all the email addresses will be copied into both "Camp" and "another" at Groups.io. Again, excluding any that are already there.
After the fiasco of the new group trials & errors I have 370, I¡¯m
afraid I¡¯ll lose them all with ¡°another new group¡±. I joined io to get
out of trouble.
The good news is that the Groups.io transfer agent copies all the email addresses from your Yahoo Group(s) straight into your Groups.io group. You don't need to invite the members, and they don't need to accept or join anything in order to receive group messages and post by email. To access Files, Photos or other web features they will need to log in to Groups.io, but that's pretty easy - nothing like all the rigamarole they had to go through with Yahoo.
The only members you are likely to lose in the process are those whose email address had bouncing status in Yahoo Groups - those don't get copied. And then, even some which weren't marked as bouncing at Yahoo may turn out to be obsolete addresses and will end up bouncing at Groups.io. But you shouldn't lose any "good" email addresses.
Shal