Source List for Multi Attachment field

[shalmaxb]

In the field type multi attachment there is a source list for the attachments, but only from Documents. I would like to fetch images from another (custom) entity, which is related by a n:1 relationship to the entity, where I would like to link the attachments.

Alternatively is there a possibility to get the attachment by formula. I already succeded to fetch the record Ids of the related record and can display those values in a list field, but how could I get the attachment Ids of these records?