There was a discussion in one of the more recent summer update discussion thread that migrated into discussing the abilities of linked up casters.
The question is do they retain their individual abilities, i.e. can a trimancer cast any spell that any of the individual casters are able to cast. Alternatively, can they only cast spells that use more than 1 caster in the link.
We never see any of the 3 Eyemancers cast any individual spells. For example, Maggie healed Parson from being tired.
However, Maggie does handle thinkagrams as part of the table, but not individual ones.
I am not sure there is much info either way, but I have shifted from thinking it is obvious that they retain all their individual abilities to think that it could go either way.