multiple installations - one time user registration

[nikitaspaloj]

I have installed 5 galleries  www.e-texnes.gr
Is it possible to have the user register one time in any of these installations and automaticly the reg information to be passed to the other 4 ??
I meen that i don't want the user to follow the register proccess in each gallery but if he will do it in one of these 5 to be registered in the rest.
I hope i explained 

[Joachim Müller]

Possible if the 5 installs all have access to the same database. Make them use the same user and groups database tables. To accomplish this, you'll have edit include/init.inc.php. However, I can't see the point in having 5 galleires on one domain in the first place.

[nikitaspaloj]

hmmm edit include/init.inc.php 
??
i meen what should i edit there and how ??
If there is any related post pleeease show me the way.
As for the 5 installations.There are different .there are and different thematics.And i can keep the, look differenet.
More i like the style and as long as they can be connected and the users and with links pointing it does not look to me bad.will that have a negative affect in something ??Cause that is a point.
But i am more interested about how i will edit the init.inc.

[Joachim Müller]

Has been discussed previously, yes. See bridge coppermine to another coppermine?

Keeping 5 galleries just for the sake of having 5 different themes is absurd - you could assign themes by category instead.