Hi @kasra,
Interesting. You might be able to do this by using just a volume number and not an issue number. I don’t think it would break its functionality, but it might be that issue number is a mandatory field (although I haven’t tested this, I don’t think it is). Some, I know are doing a similar approach with continous publishing - publishing articles as they are released and not as part of a single issue (or even volume). You might want to have a look at this post here: How to publish immediately upon acceptance - #2 by pmangahis
I don’t think that you’d be locked into a single approach with past issues. If you had back issues that did have volume/issue numbers, you could certainly keep those and then use a new model for later issues.
-Roger
PKP Team