X chromosome matching

Another set of two matches (they appear to be siblings) and a third match which may be a fourth to fifth cousin to them has come up on Gedmatch. Since there is an X chromosome match and only 2 of 5 of us match I know that this is on my mother's side since the X we (my sisters and I) inherited from our father was Rawlings and we would all match since he had only one X chromosome and it was directly from his mother.

I  am trying to decide if 8.9/8.2 centimorgans is significant. We all match one of the siblings and 3 out of 5 match the second sibling. The third individual matches us twice as much as we match the two siblings (and this is the same between the third individual and the two siblings).

If I have phased my X chromosome properly then this set of matches may belong to the Buller line but one of my brothers matches us in that same area. Why isn't he an X match? If I go in and set the minimum centimorgans to 2 and the minimum SNPs to 250 I get a 5.5 centimorgan match within the area where we are matching. Is this a true match with the three of us?

The matching segment search on Gedmatch looking at one of the siblings (best match) yields a number of matches with this set of siblings plus other members of the close family (nine in total). Probably I should write to this individual! Some of the email addresses are from australia/new zealand. There is a fourth interesting match and this is a known match with my father's father's side. But I am suspicious that I am matching this individual (tests as a second cousin) on two lines.

Writing to the individual with the nine individuals on gedmatch sounds like a plan.