I had heard Martha Hackett had a choice, she could recur on DS9 as T'Rul or recur on Voyager as Seska and since everyone was Voyager crazy at that point at the studios and there was so much buzz about Voyager and the launching of UPN she chose Voyager and the DS9 character was dropped.
I'm pretty sure Martha Hackett had no say in the matter.
I would have to agree. Why would any actor turn down a stable job like that? Yes, they're heavy make-up, but it was two recurring roles on two Trek shows, at the same time.
Commander Austin Harris, First Officer, Deep Space Nine (by FltCpt. Bossco)
8.01 - Darkest Before Dawn
(Chapter 8 added, 12/09/2015)