Without more context, it's difficult to say, but "superimpose" is used a lot in linguistics. "Overlap" would imply that the phenomena are not coextensive.

... realized by consonantal or vocalic (vowel) segments of words ... sense that they are “superimposed” upon the ... are what Bloomfield called morphemes; he defined ...
www.britannica.com/eb/ print?tocId=9110292&fullArticle=true

... Finally, a good deal of attention has been paid in recent years to the secondary perceptual effects which may arise when nasality is **superimposed** on vowels. ...
www.oup.co.uk/pdf/0-19-823848-7.pdf

Section 15.1 Linguistic Segment Categories introduces a tag set for ... phrase and clause elements **can be superimposed** on the word and morpheme tagging in ...
www.tei-c.org/P4X/AI.html

... morpheme as modifying **the lexical morpheme that it is superimposed on**, ... So far all morphemes have consisted of segments (sounds) which appear ...
www.indiana.edu/~hlw/Inflection/morphemes.html

Paradigmatic relations between speech segments are also manifested in metrical prose, but there they are optional and **superimposed onto** syntagmatic ...
www.rvb.ru/philologica/02eng/02eng_shapir.htm

The division into segments can be done using a number of techniques, ... At runtime, **the target prosody of a sentence is superimposed on these minimal units** ...
ms.wikipedia.org/wiki/Lafal_buatan