Keep in mind that if you have downloaded images from another website they may be copyright protected and those images should not be synced with a public tree on Ancestry unless you have permission to do so. (Most, if not all, subscription sites are copyright protected and even Find-A-Grave images carry copyright protection.)
I have made my synced tree private for just that reason. The procedure I've come up with is to periodically create a GEDCOM without images and upload it to a separate public tree on Ancestry. This public tree is not synced to FTM.
I have made my synced tree private for just that reason. The procedure I've come up with is to periodically create a GEDCOM without images and upload it to a separate public tree on Ancestry. This public tree is not synced to FTM.