Hello Amal,
Thanks for reaching out to us.
For your particular application, I suggest you to go through a similar example we have on coexistence of GPON & NG-PON1 which can be found at location: C:\Users\USERNAME\Documents\OptiSystem 22.0 Samples\Metro and access systems\PON and CDMA systems\Coexisting GPON and NG-PON1.osd
Let us know if you have any further questions.
Best,
Saurabh Bedi.