I would certainly assume there are “Mother Palms” for Jiang but I don’t know them. However, Kang Ge Wu, besides being a top researcher on the subject is also a major Jiang enthusiast and teacher of the style. In his Bagua course #1 he shows what his research indicates as the oldest version of the Mother Palms and I am inclined to believe him. These would go wonderfully well with the Jiang.
Personally, as a teacher, I find that the palms are extremely helpful for structuring the Bagua student’s posture, breathing and control. While not necessarily mandatory they are good enough that even my advanced students return to them for practice. Think of them as supplementary but also intrinsically valuable.
Hope this helps,
Yours in the arts,