Furloughs and seniority.
Just an historical FYI thing here.
I am not sure of today’s agreements but I do know that back in the day (my day) on the railroads, there was absolutely no confusion of any ones seniority.
During furloughs you maintained your place on the seniority list; period.
(until your recall rights expired)
Retro pay was distributed based on work during the amendable period; period.
Seniority was sacrosanct with no “warm and fuzzies” built into the contract.
It was understood that protection of any group for any reason regardless of why or what it was called, was in fact a restriction of seniority.
Moving any line is easy, the complicated part is always where to set it back down.
As a side note, maybe for the future, it might be interesting to know, they had national agreements then under a single union, as an example there was SUNA, Switchmans Union of North America (You did not carry seniority from one RR to another). And over the years dealing with interpretation issues, they actually built scenarios into the contract with the interpretation and the consequence of a violation (by the company) spelled out. Imagine that.