R1227 - Return from Org Different Than The Original Receipt Org

In R1227 return process using HTML page allows return to vendor from org different than the original receipt org.

Example, assume Org M1 has received the material and transferred the same to Org M2. RTV from M2 can be performed using Return HTML page which triggers interorg transfer from Org M2 to Org M1 and return to vendor from M1 org.

Question 1: Is Shipping Networks mandatory to setup from M2 to M1? If there is no Shipping Network, still the Inter Org transfer takes place?

Question 2: If the shipping network from Org M2 to Org M1 setup with 'Requisition' required, still the interorg transaction happens between Org M2 to Org M1 in the above mentioned scenario?