[TYPO3] BE search engine not covering multiple FE user pages?

[TYPO3]

Hi list

I'm running two websites in the same backend. I have split the FE users into 
two different sysfolders, one for each website.

As BE Admin I have no problems using the backend search function to search 
for a specific FE user, no matter which sysfolder he is placed in. But my 
webeditors (a special BE usergroup) only get results from the FE user 
sysfolder which is located in the website branch which is named on top of 
the DB Mounts they have access to..

I need to make sure that the webeditors can find any FE user they search 
for. Can anyone give me a hit as to what I'm doing wrong?

Cheers,
Lasse