If the <discnumber> is set and does not have a second disc don't use the disc number
As the title Says.
The solution is to use the totaldiscs metadata. If it exists and is greater than one, you know it's a multi-disc set.
Looks like I replied to your email anyway ;-) note the other suggested threads you might be interested in:
I just wrote a suggestion regarding this issue, which I'm pretty sure I then mistakenly sent to support. Sorry 'bout that. I was looking for a token or combination of tokens that would act as the IFMULTI in dBpoweramp. IF disc number is populated, AND disc total is not 1, THEN include disc number in naming.
I've had a few requests for this via email, thanks for suggesting it here.
I'm assuming you mean "use" for the file organisation rule.
The challenge with this is that because bliss runs rules for an album as soon as it finds it, we don't know whether or not another album with a different disc number exists. But there has to be some solution...