Possibility \#6

Possibility #6

When ṃ is followed by a vowel, it can become m or d

e.g. yaṃ + āhu > yamāhu

etaṃ + avoca > etadavoca

In Kaccāyana this is called (34) madā sare.

ṃ + vowel > m

taṃ	ahaṃ	tamahaṃ	that I
etaṃ	ahaṃ	etamahaṃ	this I
taṃ	atthaṃ	tamatthaṃ	that purpose
yaṃ	āhu	yamāhu	whatever they say
kiṃ	assa	kimassa	what is his?

ṃ + vowel > d

etaṃ	avoca	etadavoca	said this
yaṃ	idaṃ	yadidaṃ	whichever this
etaṃ	eva	etadeva	just this
yaṃ yaṃ	eva	yaññadeva	whatever at all

this is influenced by the Sanskrit yad tad etad and tam etam etc

Counter-examples:

maṃ avadhi

maṃ ahāsi