Hint for ring-group

We are running FreePBX 2.3.1 version with Asterisk 1.2.24.

We have defined a ring-group (600) for 2 extensions 105 and 108 (both SIP channel). The main issue was that there is no “hint” for this ring group and we manage to solve it adding the following lines:

[ext-group-custom]
exten => 600,hint,SIP/105&SIP/108

Our question is the following one: could be the Ring-Group module (we have version 2.2.16.2) be modified in a way to create automatically the hint for the ring-group number?

The problem we see is that when you define a ring-group you add there extensions and there is no direct links to the technology befind them. We had tried to write the hint in the following manner:

exten => 600,hint,Local/105@ext-local&Local/108@ext-local

but probably we do something wrong as we do not see (using show hints) the updated status for 600.