FreeBSD base pkg (packaging) and critical ports build alongside

Hello,

I use FreeBSD-base packages built on self hosted systems to update 13-STABLE
and CURRENT hosts.  I run into the problem, that the packages of the FreeBSD
base, built via the FreeBSD framework and from most recent 13-STABLE sources,
are often oit of synchronisation with our poudriere packaging builders, that is
especially true for critical ports with kernel modules, like i915 drm,
virtualbox and so on. The problem is, obviously, barehanded: 13-STABLE sources
and probably the API changes more rapidly than those of the appropriate builder
hosts for poudriere and since it takes a bunch of days to build a whole
poudriere packages repository, there is often a gap between the revision of the
kernel and the port containing kernel modules.

So, the question is: how can I add ports to the building process of the FreeBSD
sources tree in the way they get build every time I build the FreeBSD-base
packages alongside the OS?

Thanks in advance,

oh