Go into "edit relationship" for Louise, remove Rose as her mother, and attach Kate as her mother instead. Everyone descended from Louise will still be descended from Louise - or in other words, everyone descended from Louise will "move" with her.
The problem is that you were searching for the wrong thing, you don't want to move a whole ancestral branch, you just want to edit one relationship:
https://support.ancestry.com/s/artic...ships-in-Trees
Disconnecting wrong relationships
- From any page on Ancestry®, click the Trees tab and select a tree.
- In the tree, click on the person whose relationship you want to change. To find someone in your tree, click the Tree Search menu in the top-right corner and type in a name in panel that appears, then click that name at the bottom of the panel.
- In the menu that appears after clicking on a person, click Profile.
- In the top-right corner, click Edit and select Edit Relationships.
- Next to a relationship you want to disconnect, click the X on the right side. If you'll be establishing a different relationship between the two people you're detaching from one another, or if you’re attaching both people to different relationships, note the names of the people being detached so you can find them in your tree and connect a relationship to them after disconnecting the wrong relationship.
- Click Remove.
Reattaching people
- From the page in the last step, select a relationship to add. My Account Options
- Type the name of someone in your tree in the find a person field.
- Select their name from the drop-down menu and click Save.