I would take me a long time to reply and add my bit on the Sancho heritage. We could talk ((973) 643-5404) but here are some useful leads.
I know that the Roberts family of Mahaica are related to the Sanchos. I remember, in particular, the Sancho who was the first Coordinator of Security for LFSB. The Sanchos, his connection, also lived in David Street Kitty - Wendy and Wickham et al. were my cousins (I was told but not the history or connections) whom I visited regularly in the early 60s.
The Roberts of Mahaica - my grandfather, Walter Theophilus, was a major landowner in the village. He was the traveler, doing blasting and quarrying contract work in Nigeria, Brazil and Panama. He also owned the Seba Quarry in the Demerara River, which supplied most of the stone for the construction of the American Airbase at Atkinson Field - thereafter Timehri and now CBJ. My old aunt, Maude Braithwaite - going on 93 years of age - in Georgetown (64196), might be the best living historian. She certainly knows the Sancho and Harper and Younge (the Younges of Buxton - Weygon, Norma and Ivy) connections.
There is also a Harper connection - Monty Harper, who was Minister of Health said we were indeed cousins and the present coach of the West Indies team and I discussed our common heritage. But of course there was no follow up. I did not know of the Scotland, Denbow and other connections but they were probably part of the movement to other villages.
I also would be interested in knowing about the conditions under which the main matriarch or patriarch came to Guyana.
You are on to a worthy venture.