[Therion] join two scraps to same end of other srap

I have a passage that splits into two, with the two passages located one directly above the other. I have three scraps that join at the common passage junction. When putting together a plan I try the following; join scrap1 scrap2 #lower end white river (top passage) join scrap1 scrap3 #lower end white river (btm passage) I find that the second join statement is quietly ignored, it has no effect and no warnings nor errors generated. I suspect that I could use the more general point to point join syntax without problem, but, forever looking for the easy way, I'm tempted to ask if there is a valid reason for the above behaviour? Bruce