CHATURDHASHA VIDYASTHANAS ( knowledge system in its entirety) , does include Puranas and darsanas such as nyaya vaisheshika etc. (tantric school s do not seem to be included though)..
It is possible that one branch of a knowledge system is quite independent of another branch, owing to the difference in their subject matter. But that doesn't mean they mutually reject one other as a valid authority. for eg. Purana lakshanas may not be relatable with nyaya.
Prasthabheda and Vishnu Purna infact extends the to 18.
PurAna nyAya mimAngsA dharmshAstrAnga mishritAh |
VedAh sthAnAni vidyAnAm dharmasya cha chaturdasha ||”)Yajnavalkyasmrithi 1.3)
All the scriptures have the supreme Lord as their purport. Here the different
prasthAnas are dealt with in brief.
The Vedas are four in number—Rgveda, yajurveda, sAmaveda and
atharvaveda. The vedAngas are six—shikShA (science of pronunciation),
yyAkaraNam (grammar), niruktam (etymology), Chandas (metre),
jyoutiSham (astronomy and astrology), and kalpa. The upAngas are four—
purANa, nyAya, mImAmsA and dharmashAstras. The upapurANas are
included in the purANas, vaisheShika is included in nyAya, vedAnta in
mImAmsA, and mahAbhArata, rAmAyaNa, sAnkhya, yoga, pAshupata,
vaiShNava, ertc., are included in dharmashAstra. Thus altogether there are
fourteen vidyAs. So has it been said by sage YAjnavalkya—“The purANas,
nyAya, mImAmsA, dharmashastra and the Vedas (including vedAngas)
together constitute the fourteen vidyAs”. These, along with the four
upavedas are the eighteen vidyAs. The four upavedas are—Ayurveda,
dhanurveda (archery), gAndharvaveda (music) and arthashAstra (political
science). These only are the prasthAnas for all Astikas. (Prasthabheda Translation Sri SN Saastri)
The well-known poetic work Naisadham mentions that Nala was conversant with these fourteen branches of learning. The poet (Sriharsha) plays on the word "caturdasa": he says that "Nala accorded caturdasa to the caturdas-vidya"(Hindu dharma the universal way of life part 5 chap 3)
PS - it also true that some streams, partially accept/reject the other.