Most sources identify Margaret Lecky as simply "daughter of Lecky of that ilk". The only evidence for her first name comes from James Stewart:
"Firm evidence of the early Stewart interest in the Glenbuckie estate dates from an instrument of resignation of 15 October 1552, drawn up at Perth by Patrick Stewart of Glenbuckie and his wife Margaret Lekky, in favour of their son Robert Stewart and his spouse Katherine Kennedy." -- Settlements of Western Perthshire, by James Stewart, page 132 (http://wc.rootsweb.ancestry.com/cgi-bin/igm.cgi?op=GET&db=ryk%5Fbrown&id=I1892)