Does Highgrove have an emblem or symbol? Something akin to the Pale King's insignia for Hallownest, or the orb of silk for Pharloom?
There is this three petal flower shaped brooch, usually worn around collars or chest of accessories or outfits usually in pale pinkish color. White Magnolia and anyone associated with them specifically have a white one (so everyone in the drawing above would have it because they relate to Alyssum)
It's a very simple one!
(Bonus: while the symbol is the association, the number of gems on the mask that's also present in the doodle is the ranking. Only those working under Queen Magnolia have those and there is always uneven number of them on the mask. Seven gems is the highest rank right bellow the queen who has a crown. How they're placed on the mask can vary)