When dealing with single roles in the from and to role positions (for interactions or choice), the projection is simple.
However if there are multple 'to' roles, for example:
M1 from A to B, C, D;
If projecting at A, then this would be:
M1 to B, C, D;
But if projecting to C, I assume it would be:
M1 from A;
So, if the projected role is in the 'from' role list, then we don't project any of the roles. Representing the fact that each of those participants is simply expecting to receive a message (M1) from A. They don't need to be aware of each other.