Where does “instealing” come from?

instealing (English) comes from English steal, from Middle English stele, from Old English stela, from Proto-Germanic stelaną, from Proto-Indo-European tsel- — to sneak.

instealing (English): entering or manifesting surreptitiously

Definitions

entering or manifesting surreptitiously

Ancestry of “instealing”, step by step

instealing traces back through two separate lines of ancestry.

via English steal

Step	Language	Word	Meaning
1	English	steal	To take illegally, or without the owner's...
2	Middle English	stele	steel
3	Old English	stela	stalk (of a plant)
4	Proto-Germanic	stelaną	to steal; to sneak
5	Proto-Indo-European	tsel-	to sneak

via English in

Step	Language	Word	Meaning
1	English	in	Used to indicate location, inclusion, or position...
2	Middle English	in	Any kind of accomodation; particularly; A home or...
3	Old English	in	in; Alternative form of inn
4	Proto-West Germanic	*in	—

Every word from Proto-Indo-European tsel- →Every word from Proto-Germanic stelaną →Every word from Old English stela →