import database into another

it will make it a tad difficult but is doable, there are different merge approaches one is i.e. you remove primary key from the 7.5 database, make it a normal into field, then in every table that had a pk just add (max primary key of 7.8 + 1) to it so there will be no pk clash in the final result. After you did that you can just use dts for sql or copy paste in access for all tables you want to merge. for the forums itself be careful that you update topics and posts to look at the right forum once you changed the pk.