My grandmother was Emily Mahalie Isgrig from Potosi,Mo.
Checking back against the Isgrigg names you show, I'm certain that your Isgriggs and my Isgrigs are from the same line and go back to William Isgrig I, London, England about 1680.
If you don't have this information and are interested, please give me your e-mail address and I'll provide you with all the 'in-between" particulars.
Mitch
nwiles@pacinfo.com