Marvel Comics Presents #43 has been a bit of a frustration for me in the past because I've tried to file in my collection in accord with Siryn's backstory.  The problem I constantly found was that certain checklists would rank her story in this issue as occurring after she joined X-Force.  I can accept this knowing that we don't get too much on Siryn in those early books and it's feasible that she went back to Ireland a time or two that we just weren't told about.  Yet, I could never get the issue placed in that continuity without disrupting the flow the X-Force books had.  A story about Ireland in between Cannonball's death and then Siryn's abduction by Gideon just didn't jive.  
 
This problem was simply exacerbated by the fact that the MCP issue was printed a year before this supposed time.  My concern with simply putting this issue where time would have put it was that Siryn was supposed to be on Muir Island and we as readers didn't have too much knowledge into what was happening there at the time ( Moira had been noted as acting strange for months before).  So simply putting Siryn in Cassidy Keep while she was supposed to be on Muir acting odd also didn't jive because it felt a little pretentious to state what could have been happening.  
 
Then I read the " Kings of Pain" cross-over.  I never used to read the old annuals but this opened my eyes some.  Not only does the X-Men Annual ( #15) tell that Banshee was missing (a point in the MCP issue) but it could also explain why Siryn would need a bit of a break.  Proteus was quite the obstacle, a little downtime could have been very practical.  
 
So, based on continuity and intuition, I say that, at least for Siryn fans going after backstory, this issue of MCP should go right after the "Kings of Pain" crossover.  I don't know how well that will go with the other three stories but I don't read this issue for them anyway.