In case of group Companies, can employees of parent company work in subsidiary companies and what is the HR Operations process needs to be followed

In case of Group Company, can employees of parent company (A) work in subsidiary companies (B, C, D, E) and what is the HR Operations process needs to be followed.. it will be of great help if someone can guide with the formats and processes to be followed.

Dear sir,
Yes, services of an employee can be transferred, if there is Transfer clause in the Appointment letter . or as per conditions mentioned in certified standing orders .Please note that provisions of applicable standing orders is to be interpreted with respect to categories of employees classified therein.Standing orders is not for employees in management staff .Also, the terms as mentioned in Appointment letter shall prevail over the provisions of Standing orders.
So, it would be undisputed if transfer clause is well signed off while issuing employees the Appointment Letter.
Regds,

In addition, the important point to be noted that there shall not be any adverse change in service condition like pay, status, weekly hours of work as a consequence of transfer and the transfer shall not be motivated by bias, prejudice or malafides.