Feature request - snippet support for custom fields

In MoreGallery, I am using a custom field which includes a list of artists and the id of their page so that I can link the images in group galleries back to the artists page.

{"artist": { "label": "Artist Name (required)", "type": "select", "options": [ {"label": "None", "value": ""} ,{"label": "name1", "value": "42"}, ..... }

This produces a pull down of names and stores the ID which makes linking easy.

What would be very useful is to use a snipped to define the custom variables so that the list of users is automatically updated as users are added to the site.

I know resources work in the the Media Sources but not in the MoreGallery custom fields.

Any ideas on who to enable that it?