Chinese is replete with homophones. Some seem to be cognitively related. Let’s have a look at the phoneme yu2, usually in second tone.

于 余 与 all three are yu2 and are high frequency connecting characters! AT, EXCESS, RECEPTION
与 AND  宇 yu3 universe (image: a child underneath the sky-dome!.
与 PARTICIPATE 欲 yu4 DESIRE

于

AT, In, From. Can also function as a question particle like ma at the end of a sentence, that usage however seems literary to me as opposed to colloquial.

余

Extra Surplus Excess, Left over goods. Image is a house under construction with surplus material scattered about. AT this House is EXTRA construction material.

与 yu2 yu3 yu4

PARTICIPATE yu4

AND yu3

This one is the idea of mutuality, especially the mutual relation of reception by the younger generation from the donation of the elder generation.

欲 yu4

Desire.

宇 yu3

Universe.

雨 yu3

Rain