I think you can take it as read that Janet Erskine was the daughter of Mary Maxwell of Nether Reddick and James Kennan. The Erskines clearly provided evidence to the Court of the Lord Lyon to the effect when they were granted/matriculated arms with a Maxwell of Nether Riddick quartering. I believe on of the Erskine grandsons became Sir John Maxwell Erskine of Rerrick later Lord Erskine. The Lyon Court in Edinburgh might be able to supply a copy of the pedigree from the matriculations in the Register of All Arms.