This is what you want to know -
(back center panel) p1, pm; p2, pm; p2, c4b, p2, pm; work est. Lace Rib Pattern across 15 sts, pm; M1, k18, M1, pm; work est. Lace Rib pattern across 15 sts, pm; p2, c4b, p2, pm; p2, pm; p1;
For the lace rib pattern you just continue on in its chart wherever you were when you got to this point.
sue- knitting heretic