In LIS full relative clauses, the manual relativisation sign pe does not inflect for the singular/plural feature of the head noun. Even in the presence of a plural referent, the sign pe is invariant in its form. In the example below, although the head noun child++ is plural, the sign pe agrees with one point in the signing space associated with the head noun.
rel
[child++a win pea] teacher prize give
‘The teacher gives the prize to the children who win.’ (recreated from Branchini, 2014: 192)
As for LIS free relative clauses, wh-signs are specified for the singular number feature.