Need help with belongs_to , scoped target and paramater

i have a belongs_to which reference a key-value par table, itself scoped too by various parameters. one of them is variable though:

Class SysType
scope :scope_sys_FLEET_VEHICLE_TYPES, -> (cid) { where(keyscope: ‘FLEET_VEHICLE_TYPES’, :company_id=>cid ) }

belongs_to :scope_FLEET_VEHICLE_TYPE, ->(o) { (joins(Systype.scope_sys_FLEET_VEHICLE_TYPES(o))) }, class_name: “Systype”, foreign_key: “vehicle_type_id”, :primary_key=>“id”

–> my problem is the lambda / parameter going into the belongs_to, whether i do it with (where(blah=>?",o) or whatever - i cant get it out…

reason why i am doing this, is i want to build the form automatically, whenever reiterating over a ‘belongs_to’ ill can get the data from the scope…

any ideas?