Is it safe to add new columns to vbulletin users table?

[SwalyAaron]

I have a script that isn't related to vbulletin at all, it adds information in a seperate database.

Today I was thinking what if I add some of the information I submit to this database to the vbulletin users_table to keep track of things?

Basically this is what I'm doing

Someone uses the paypal IPN I've setup, information is submitted to a DB name "payments", one of the columns is "price" so I was thinking if I can do this

$totalpayed += $price;

and add $totalpayed to the vbulletin DB so I can display it in say Usercp later on, or add it to the vbulletin user array for other manipulations.

Can this be done or is it too risky?