You would like to do custom development for Sales Quote (CustomerQuote ) party in SDK, and you find the "CustomerQuote.Party.PartyKey" element is Read Only.
SAP Cloud for Customer
You are not using CustomerQuote party in correct way.
You need to use PartyKey-PartyID-Content instead of PartyKey.
CustomerQuote, Sales Qutoe, Party, SDK, PSM, write access , KBA , LOD-LE-CQP , Customer Quote Processing , How To