Retrieve data from two Tables and validate

I'm in a similar situation.

I have a user table :users with crucial login info, and another one
for profile data :members. :users actually belongs to a plug
in; :members is mine. I could put all the info into :users I suppose,
but what I really want to do is to keep them separate but still enjoy
the benefits of Model and all the form handlng and CRUD goodness. I
thought maybe

class Member < User
...
end

would do it, and it does, provided I put all the data in :users and
Member just allows me to not mess with the plug-in's source.

Can a model be associated with 2 tables?