Your tree has not been changed with ThruLines(TM).
What’s white is from your tree. What’s gray is from other trees in the set of trees at Ancestry.com. ThruLines(TM) indicates the submitter of the tree from which the “is box” information has been obtained.
Those gray boxes are showing you the suggested connection between the DNA test kit you submitted and the DNA kit that matches yours.
The displayed relationship may not be correct. It is up to you to check it out with other records and information.
Thrulines(TM) is giving you a suggestion. It is not changing your tree. It’s up to you to do the research.