How to change echo result by hook in template

Hi,
In the bp-groups-template.php is a loop to display the groups, the names of the groups are echoed there.
I want to adjust that echo.
Here is the original function in the template:
function bp_group_name( $group = false ) {
echo bp_get_group_name( $group ) ;
}
I have changed that into:
function bp_group_name( $group = false ) {
$naam = bp_get_group_name($group) ;
$naam = str_ireplace(“*”,”
“,$naam) ;
echo $naam ;
}
Works great.
But… this is still in the template itself.
How can I make a hook of it? (with add-action) And can I place that in the child theme?
Thanks for help!
Pieter