Linking up SMF user lists?

[AdamXUF]

SMF Version: SMF 1.1.3
What i have attempted (But failed) to do is link two forums member lists together.

The two forums are on the same host and same sql.

Example:
Bob registers on forum A, and it automaticaly registered on B (Because it uses the same member sql)

I replaced every appearence of {$db_prefix}members [on forum a] with smf_1members [forum b's sql]. But it didnt seem to DO anything! They still have their own independent user lists!

Thanks if anyone could point me in the right direction.

[AdamXUF]

Thank you for been so extremely helpful -

[jerm]

Share user database for 2 (or more) different forums.