Hello,
I think many people are willing to help you, but when we don't know what you have it is impossible. When is an OEM filter, the datasheet may not be in the public domain. Did you try to contact the vendor?
If you have the filter, try to measure it yourself. When you don't have a VNA, carry out a scalar measurement of S21 and do a S11 measurement based on a slotted line or other cost effective method. When you have more filters, dismantle one to see the number of poles and coupling method.
With this info you can model your own filter and you continue with your project. your posting is from March 23, so it is likely that you have to do it yourself.