I propose based on the book of Wallace that this first Adam in the Wallace line is Grandson of the original Richard of "Riccarton" (1st of Riccarton). He had second son Richard, (2nd of Riccarton) who is Adam's father, making Adam 3rd of Riccarton.. I believe there is an extra Richard in tree. Adam had a brother named Richard, who received the lands of Auchencruive and Hackencrow. Adam had 2 sons Adam (and Malcolm)-who succeeded to Riccarton.
The Book of Wallace spells it out quite clearly, and then you can follow the different Wallaces in the different towns.
I have what I think to be appropriate dates in my Wallace Family Tree on ancestry.