How to map give_way/yield spots on turn lanes

Situation: when approaching a junction, the road goes temporarily from 2 to 3 lanes, 1 backward, 2 forward. the forward is left|through. The left turn lane has a yield spot painted on the road. How does one tag this... give_way:forward=yes|no or left| or is this OTT? The give_way:forward=left has only ever been used 4x. give_way:forward/backward=right 11 times. There's even a give_way:lanes:backward=no|yes. Ignoring the lanes part in the cases that would become give_way:forward=yes|no which seems a plausible solution.

TIA