[Query] What is the relation between mata kubjika and saptashati?
None directly, I can think of, when saptashatI is considered in its entirety. But kAtyAyanI tantra defines saptashatI as saptasatI due to the presence of seven satis of shaktis of shiva in each of the three charitas. These three sets of shaktis are:
brAhmI, mAheshvarI, kaumArI, vArAhI, vaiShNavI, aindrI and chAmuNDA
lakShmI, lalitA, kAlI, durgA, gAyatrI, arundhatI [tArA] and sarasvatI
kAlI, tArA, ChinnamastA, sumukhI, bhuvaneshvarI, bAlA and kubjikA [baDabAnale, vArAhI tantre]
nandA, shatAkShI, shAkambharI, bhImA, raktadantikA, durgA and bhrAmarI
Apart from naming these shaktis as present respectively in charitratraya, the tantra says: mahAmantrAH guptarUpeNa kIrtitAH | nIlakaNTha and svarUpAnanda bhAratI, two commentators on kAtyAyanI tantra, discuss the uddhAra of these mantras from saptasatI. bhAskara hints at these here and there in guptavatI as well. So, this is the only association of pashchimAmnAyeshvarI with saptashatI I can think of. Interestingly, the pashchimAmnAya text that I follow lists the following among the dozen anga vidyas for navaratna kubjA:
chaNdikA chaNDamAta~NgI dhanadA padmadhAriNI |
chaNDikA figures here, but with a slight difference in mantroddhAra. praNava is explicitly prescribed before navAksharI and this vidyA is always referred to chaNDikA dashAkSharI. This usage, as explained by an adept from Gujrat, should be understood as valid only in the context of kubjikA mantra and not generally when dealing with saptashatI or chaNDikA.
atha chetsarvapITheShu kubjikA samayAtmikA |
asyAH smaraNamAtreNa vihvalaM tu jagattrayam ||
kubjashrIsahaitaM balIndradamanaM mAyAmayam vAmanam || - bhaje