Family Historian User Group

I have two GEDCOM files, one for my daughter and one for her husband including their son.
How do I join them together to create one tree that contains both groups?
Ver 5
genesnz

Hi Folks,
Family Historian v5
Open the Focus Window
Go to File
Go to Gedcom File Tasks
This brings up a list of files showing available family trees.
How can I delete those files that are no longer needed??
Kindest regards
genesnz