Laravel baum modify tree on the flow without saving the changes in DB

Using Laravel etrepat/baum I would like to modify on the flow the tree but without saving the changes in the database.

When I save the tree I save a value as boolean if an element is the root of the abrevated secondary structure and the idea behind is to redifine the hierarchy and return the new structure as json

- Category-A

-- Category-A1

--- Category-A11

-- Category-A2

--- Category-A21

-------------------------------------

- Category-B

-- Category-B1

--- Category-B11

-------------------------------------

- Category-C

-- Category-C1

--- Category-C11

-- Category-C2

--- Category-C21 

desiered structure would be

- Category-B

-- Category-A

--- Category-A1

---- Category-A11

--- Category-A2

---- Category-A21

-- Category-C

--- Category-C1

---- Category-C11

--- Category-C2

---- Category-C21 

What is the best approach to achive the desiered result?

via Chebli Mohamed