Select the first keyword collection, then press cmd-key (next to spacebar) and then select (click) the other keyword collections (or smart collections).
If the lavalier is the only source of audio you only need to use one channel (“track”) since it is a mono source. With the clip selected, open the inspector and under the audio tab select the Channel Configuration and there change the audio to Dual Mono and disable the weaker track. Now the lav plays equally from both speakers.
Make the audio as one polyfile. The multitrack audio editing in FCP X also works best with polyfiles. Sound Devices WaveAgent software can batch do it.