First-line and Uppermost

First-line adjective - Singled out from a number or group as more to one's liking.

Uppermost and first-line are semantically related. In some cases you can use "Uppermost" instead an adjective phrase "First-line".

Uppermost adjective - Being at a point or level higher than all others.

First-line and uppermost are semantically related. Sometimes you can use "First-line" instead an adjective "Uppermost".