Some grammatical works use the sign "ᳲ" for Upadhmānīya and Jihvāmūlīya, and these are described as ardhavisargasadr̥śau. If I remember correctly, the Vājasaneyi-Prātiśākhya says that these two do not occur in the Mādhyandina-Saṃhitā, probably indicating that they do occur in the Kāṇva Saṃhitā. So it is possible to find them in the manuscripts of the Kāṇva saṃhitā.