If, as you say, the second posting of Sandhiils is declared invalid, then the posting of Kirkdale, that was made after the posting of Rice Lane, appears to have been the last valid posting.....and all postings after this point are thus deemed to be invalid.
It is not just the second posting of Sandhills, but the following start of a new leg and subsequent postings on that leg, plus any other postings, should now all be deemed invalid and the next posting would be the outward station posting from Kirkdale on the Ormskirk line, which should be made after this clarification posting.