Originally I was going to try to make a custom script. The idea was that I would be able to put a table like the following in the GM Notes of an item or feat handout. The
GIVE ITEM link would send an API command that, while a token is
selected, would pull the info from the table and make a new item in the
specified repeating section, filling the fields named in the left column
with the text given in the right column. The API command in the link would need to be
manually entered as well with the handout's ID. Then keithcurtis pointed out to me that ChatSetAttr can create and fill repeating rows already. This sounded much more simple than what I had planned, but I wanted to avoid having to make a unique macro for each item. So I got the idea to store the custom items in the appropriate repeating sections in a character sheet. I'd call the sheet 'compendium' and have a handful of macros with a command like the one in my initial post—one for feats, one for spells, one for magic items, etc. Ideally the macro would ask what row number the item is stored in, and then use that to determine the attributes to find from the compendium character sheet, parse through the command, and add to the selected character's sheet.