It appears you may be confusing MP ratings with a Multi Pilot Licence (MPL) which as pointed out is more restrictive.
You should read the Regulations of the Administration that you wish to obtain your licence under.
As the MPL is an EASA licence, all the regulations can be found here:
https://www.easa.europa.eu/sites/default/files/dfu/Easy_Access_Rules_for_Flight_Crew_Licensing_Part-FCL.pdf