We know that Charlotte McLauchlan's mother is Elizabeth Kelly (possibly formerly Wylie), and that she was born in Ireland, no marriage to Charles McLauchlan [McLachlan] has been found to date. Elizabeth has been names as both Wylie and Kelly various BDM records of her children, which leads me to believe she may have been married previously.
See Elizabeth Kelly's descendant chart below:
Possible spelling variations for the McLauchlan name are:
Mclaughlin, Mclaughlen, Mc Laughlan, Mclaughland, McLaughlane, Mclaughlan, Mclaughler, McLaughley, McLaughlien, Mc Laughlig, Mclaughlihn, Mclaughliln, Mclaughlim, Mc Laughlin, Mc-laughlin, Mclaughlinadam, Mclaughlinarye.