I had very little information on the Guestsuntil I joined Ancestry.Com and found that there is a huge amount of info out there and I am in touch with several connections to the family.
I have a huge amount of info on the Frist Guest Edward who came from Ireland and quite a bit of history.
Can you get in touch with me on my email and give me your address so I can forward all I have so you can then work out where you fit in.
I am still trying to work out who gertrude amelia Guest's Father is!! (she is my grandmother maternal who would not give me any information about her family.
I can see why now as the family had multiple marriages and marriage between relations was quite common in the Guest side of my family and yes you are right very entwined with the Gidneys. In those days all this was frowned upon. I wish though she had divulged her ancestry it would have made life so much easier.
I am in touch with one survivng Gidney/Guest who lives in Perth she is a walking encyclopedia and her memory is fantastic. She is in her 80's and unfortunately not long for this world as she has cancer.
If you send me more details about your connections i will call her up and find out if she remembers anything about your side of the family