Declension table of ?upastheya

Neuter	Singular	Dual	Plural
Nominative	upastheyam	upastheye	upastheyāni
Vocative	upastheya	upastheye	upastheyāni
Accusative	upastheyam	upastheye	upastheyāni
Instrumental	upastheyena	upastheyābhyām	upastheyaiḥ
Dative	upastheyāya	upastheyābhyām	upastheyebhyaḥ
Ablative	upastheyāt	upastheyābhyām	upastheyebhyaḥ
Genitive	upastheyasya	upastheyayoḥ	upastheyānām
Locative	upastheye	upastheyayoḥ	upastheyeṣu

Compound upastheya -

Adverb -upastheyam -upastheyāt