Question Groupmanager, How can I configure it so people spawn in their subgroup's spawn?

Hello, I have a question about groupmanager.
On my server I use groupmanager to devide the players into sections like for example elements.
No problem with that, until I added ranks in the server, like donator. Now, the players are in the groups of their element, without subgroups. this way they can use /spawn to get to the spawn of their element. Players with for example donator rank need do have their rank as main group, otherwise other plugins (for example votes-GAListener) won't work with permission stuff. So that way the people with ranks have their rank (for example donator) as main group, and their element as subgroup. Now comes the problem that this way a donator from Fire and a donator from Water both have the same spawn, and I don't want that. is there a way to have the players use the spawn from their subgroup instead of the spawn of their main group? I appolagize for my bad English, It ain't my native language. I would be really glad if you understand what my problem is and if you would be able to help me with my problem.
Greetings,
Kjell