There are two things you can do, combine or transplant. These answers suggest a command line; you may have to search through the menus in the turtle to find similar functionality.
You can merge all changes from one branch to another. The procedure for this:
hg update mybranch
hg merge default
hg commit -m "Merging with default"
, , . ,
hg update default
hg merge mybranch
hg commit -m "Bringing in changes from mybranch"
, , "", .
[extensions]
transplant =
, :
hg log | less
hg update mybranch
hg transplant 88660cca467d