4 plesk Server and 2 DNS Server

good day.

I will have 3 or 4 plesk server. Will but only 2 DNS servers for all Plesk servers, so that the Registrar always the same two DNS servers can enter. how do I do that? I have read at 2 plesk server one can mutually plesk master / slave reciprocal. But I have 3 or 4 plesk server.
Pleskserver1: x1.domain1.com
Pleskserver2: x2.domain1.com
pleskserver3 x3.domain1.com
pleskserver4 x4.domain1.com

DNS Name for enter by registrar ns1.domain1.com (Plesk Server 1) / ns2.domain1.com (...

4 plesk Server and 2 DNS Server