Convert children's room into bathroom

Hello, we want to convert the current children's room in our house into a bathroom, if possible. Right next to the children's room there is already a guest WC, so theoretically there are already pipes very close by. Possibly one could make an opening at the wall (1) of the guest WC and thus open the room so that it is all one room. Alternatively: leave the guest WC as it is and install another toilet in the new bathroom (if possible). In the bathroom created this way, a shower should be installed at D, a washbasin at W, and a corner bathtub at E. Additionally, a connection for a washing machine should be installed in the bathroom. Our question now is: is this even possible? What exactly would need to be done (chiseling walls, laying pipes for supply and drainage, etc.) and what would the approximate costs be? Our main concern here is the installation of the necessary pipes, supply and drainage. Can the connections only be made on the wall where we have now drawn the fixtures, or could the washbasin, for example, also be installed on the opposite wall? See plan.....
Best regards, Michael

Hello Michael,
the wall where the shower, washbasin, and corner bathtub are to be installed, is it an interior or an exterior wall?
What is the wall thickness?
Regards,
Dirk