PC 1864
I want to do the following:
Zones 1, 2 on partition 1
Zones 3, 4 on partition 2
Z 5, 6 on part. 3
Z 7, 8 on part. 4

How can I do that? Thank you.

I don't do much Partitioning, and work more with the PC5010/1832.
But the least you will need to do is in Location (000) at each Keypad Enroll as:
KP1 will be 11 (Partition1/Slot1)
KP2 will be 21 (Partition2/Slot1)
KP3 will be 31 (Partition3/Slot1)
KP4 will be 41 (Partition4/Slot1)
And in location 201, enable 1,2,3 and 4.
Are you using Keypads, or a zone for arming? FOB's are also possible.
If Keypads, you may need 1 of 2 delay times for Zones 1,3,5 and 7.
01 for delay one's time or an 02 for the second delay time.
I'm guessing, is this for 4 offices, each with an Entry Door, and 1 motion?
Good Luck