Declension table of vastavya

Neuter	Singular	Dual	Plural
Nominative	vastavyam	vastavye	vastavyāni
Vocative	vastavya	vastavye	vastavyāni
Accusative	vastavyam	vastavye	vastavyāni
Instrumental	vastavyena	vastavyābhyām	vastavyaiḥ
Dative	vastavyāya	vastavyābhyām	vastavyebhyaḥ
Ablative	vastavyāt	vastavyābhyām	vastavyebhyaḥ
Genitive	vastavyasya	vastavyayoḥ	vastavyānām
Locative	vastavye	vastavyayoḥ	vastavyeṣu

Compound vastavya -

Adverb -vastavyam -vastavyāt