to counsel, to consult together, to take part in, to intervene
叅 centers on the act of joining in with others to give advice or deliberate together: counseling, consulting, participating, or intervening in a matter.
叅 is a variant form of 參, which originally depicted three stars (the constellation Shen) and later acquired meanings of joining or mixing. The exact development of the variant shape is uncertain.
The bottom component ⺗ looks like a heart, and the upper part suggests multiple people. Imagine several people bringing their hearts together to counsel and consult one another.
For サン, picture a group sitting under the sun (サン) to counsel together: sun -> サン, and they all take part in the discussion.