Network nodes and methods performed therein for handling network functions

A method performed by a first network node in a communications network, for handling Network Function (NF) service requests over a roaming interface. The first network node is arranged in a service producer domain of the communications network. The first network node obtains, from a second network node located in a service consumer domain of the communications network, a discovery request for a service located in the service producer domain of the communications network. The first network node retrieves an address of a NF service producer node providing the requested service, wherein the NF service producer node is located in the service producer domain of the communications network. The first network node generates a first Uniform Resource Identifier (URI) by appending an address of the first network node to the address of the NF service producer node. The first network node provides, to the second network node, the first URI.