Is there an easy way
 

to merge different ancestry trees.

I have quite a number of trees

OH's
Mine x 3
Children's outlaws x 2

and I would really like to consolidate them into one big tree.

I have FTM 2019

I think you would need to download them all from ancestry and then merge them together in FTM one by one, then upload the finished result back to ancestry.

I can't see how I can merge even one tree with another Kite - so it maybe that I have to add everyone's details one by one manually.

No, there will certainly be a way to merge trees since it was possible in previous versions of FTM, Julie. I don't have FTM 2019 so I can't give you exact details, sorry.

I only have the books for FTM2014 and it doesn't seem to show how to do it in there.

I have the disc for FTM2017 but only the download for FTM2019.

In FTM 2011, it is File > Merge.

Thanks Kite

I've managed to merge two trees, which is great thanks.