Cross-Referencing two haystacks of vectors

I would appreciate guidance in resolving my cross-referencing lists.
Haystack #1 is a list of X vector sublists (9) with one single Y vector ‘mixed’ in.
Haystack #2 is a list of Empty sublists (4) with a sublist (5) of X vectors with it’s own Y vector. This Haystack may vary to have 1-3 Y vectors eventually.

Goal: establish a Boolean mask confirming which indices of Haystack #2 align with Haystack #1 vectors. I need to use the mask to build the relative list, aligned to Haystack #1 indices.
i.e. Build list, aligned to Haystack #1 indices, of only Haystack #2 aligning indices.
Imagery = All #2 nails to #1 nail, all #2 screws to #1 screw etc…

Auto lacing results not aligned to #1, only 5 sublists
Short lacing ditto
Long lacing has a sublist of 9, but no ‘correct’ answer aligned to Haystack #1 index
Cross-product lacing ditto.

I’m not sure how else to proceed in order to automate the finding / aligning of indices.
This is a summary of a more complex workflow. This is the core challenge.

As a new user, the system restricts my upload rights. I hope images suffice.

Thank you in advance for your time.