select entity to connect to a specific modded block/s, later execute a command from the GUI of the block/s (see desc)

hello,

i want to select entities to connect to a specific modded block, to later execute a command on them from the GUI of the block

i had a system, which gives the entities an nbt tag with the block coordinates, that worked great but had one problem: i want to be able to connect one entity to more than one block.

does anyone have any ideas on how to achieve that?