Accidental re-assigning of Parent Function

I created a LDFB from a parent function A that had one child function.
I then added two other “sister” parent functions, B and C, to the diagram that each have one child function also.
Somewhere in this process I’ve mistakenly allocated parent B to be a child of parent A (unfortunately hitting save long before I had realised my error). I think I did this through positioning the functions on the diagram but I can’t be sure. On this LDFB diagram I can’t simply move parent B out of parent A (attempting to do so shows the movement as grey and releasing in the grey doesn’t work). However parent C remains on its own under Root Logical Function and can be moved around the white space on the LDFB diagram that surrounds parent A. I havern’t tested putting parent C inside parent A because I will have the same issue!
Help me revert my mistake and free parent B!

Hello Peter,
If it does not work from the LDFB (which by the way would require a update of Capella in order to allow it), you can do it from a breakdown diagram (LFBD), or from the Capella Project Explorer (by drag & drop the function C under the Root Logical Function)

Thanks again Aurelien!
That seems easy enough - I was blinded by the LDFB creating the issue in the first place yet apparently not allowing the issue to be fixed. Strange.