subprocesses

Hello dear readers! i really need your help

basically i am stuck

Imagine a bsuiness processes mapped with 5 several task. Each task has certain subprocess. Now task 2 and task 3 and task 5 share ONE  exact same subprocess (let it be called "pay bank"). Is it possible in the free version of aris express to have this subprocess in a separate general file, as to always be able to refer back to it. What I am saying is that that I dont have to copy it three different times. Also if I would make a change in the subprocess "pay bank", Id have to change it again gor the other two copies of it. But can I have one general file as pay bank subprocess which i can always refer to ..so when i make a change in subprocess "pay bank" attached to task 2, it automatically changes also in the subrpocess "pay bank" attached to task 3 and 5.. ?   please help my boss really wants to know! and he comes back and asks me everyday but i cant give him answers...