Can we fetch value from OSC to OPA For unrelated Contact Object fields?

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We have to map 1:1 relationship mapping between OPA Attributes and OSC Fields.So my question here is even if we map the 1:1 field mapping between OSC and OPA can we fetch the unrelated Contact Custom Object fields(data) into OPA interview page ?

PFA  below where Model Field is Unknown as the Mapped in field of Model Object is not having relationship with Contact Object in OSC.
OSC Object association example: 
Contact Object is a parent for vehicle Object so we can fetch field value from OSC Field to OPA Attribute 
But when i fetch the value from Model object (not associated with Contact Object) i could not fetch/get the value from model fields even we mapped with OPA .