Most sites about Lazarus show that his wife Margaret was the daughter of Charles and Margaret Harris. Working through historical data, Sir Robert Stewart 1588 of Culmore is well written and through several resources, Lt. Colonel George Stewart 1622 was the only son of Sir Robert. George had a daughter named Anne who married Rev Henry Maxwell. No much mention about sons. Ref: Peerage & Baronage, Burke 1880. According to John Lodge, Peerage of Ireland, 1789, Vol 6 Page 244, George married Lady Ann. No mention of Catharine Barkley.
Time line on your site shows Sir Charles Stewart m Margaret Harris. Charles born 1666 and Margaret born 1670. Lazarus born 1683? and if so, Charles would have been 16 at the time of his birth & Margaret would have been 13 years old at the birth of Lazarus. Other sites indicate that Lazarus was 1 of 12 children with several others being older. Just the time line of Charles & Margaret do not make it plausible that Lazarus would have been their son. Citing your sources would be very helpful.