Urgent Need - Link/Mirror Items as Subitems (w/efficiency)

Hi All,

I have 2077 items in one board that I need linked/mirrored as subitems to another board of 551 items. I lost my administrative staff due to COVID-19 and I need to figure out how to quickly execute this myself.

I know I have the ability to link each individual item, one at a time, but with 2077 items - I just don’t have the bandwidth.

Has anyone found a solution or a workaround for this? I’d be forever grateful for any insight.