About the only manx documents of this period I have ready access to are the manorial roll for 1633 German + 1643 composition book - 'the' is seldom used as mostly lists of names; however in the composition book many entries use the (or that etc) but one or two entries use 'ye' or 'yt' and definitely in these it is not a combined th - you can see the old style th (as two letters) in Tho[mas] etc which looks a bit like an upward line followed by a strange 'g';