systemMayContain and MayContain

Hi

I have a interforest migration scenario with a 15 year old domain where there are 100 custom attributes that are bound to a class.

Source domain is FFL and DFL 2003

In the source domain the class have all 100 attributes in systemMayContain 

Target domain FFL and DFL 2008R2

When I create the class (Auxiliary-Class) in target all attributes I add are placed under MayContain instead of systemMayContain in the source, when I have been reading about this it has to do with inheritence from the Auxiliary-Class

Will this cause any problems later on?