My <Conductor [surname]> is a virtual tag that will break down (up to 4 levels) the <Conductor> tag to just the surname.
$IsNull(<Conductor>,,$IsNull($Split($Replace(<Conductor>," ",|),|,4),$IsNull($Split($Replace(<Conductor>," ",|),|,3),$IsNull($Split($Replace(<Conductor>," ",|),|,2),$Split($Replace(<Conductor>," ",|),|,1),$Split($Replace(<Conductor>," ",|),|,2)),$Split($Replace(<Conductor>," ",|),|,3)),$Split($Replace(<Conductor>," ",|),|,4)))
For composer's names, I use the sorting tags so I can use the full name with <Composer> and the surname with <Sort Composer>.
eg: Alessandro Scarlatti >== Scarlatti, A.