Alicia:

I have been doing a lot of lateral research as well, particularly in 
the earlier years (1700s) because as Emily points out, there is a lot 
that can be found out by tracing migration and marrige patterns within 
a family and across families.

I have a lot of intermarriage in my ancestry as well, with nine 
different lineages leading back to the same man around 1700.  Other 
than this man having had many children, the families in this rancho 
(Charco Hondo) seemed to marry with each other over the generations.  I 
am not sure that this has to do with fiefdom, because this particular 
man was a rather large landowner and I am assuming his children were as 
well, but by the late 1700s land had become scarce in the area and 
marrying out would mean having to distribute land into even smaller 
parcels in following generations.

I also think that family unity probably played a role... migrating 
would usually require moving not just yourself, but your extended 
family.  That, I have witnessed anecdotally and read about in academic 
studies regarding migration patterns from these ranchos to the United 
States.  Each rancho has one (or sometimes two) target places in the 
United States where people migrate.  That way, they are able to move 
with their family units and support systems intact.

I have now connected with the other two Pinedos from the group and we 
are collecting data on all of the Pinedos in a given period (mid-late 
1700s) so as to find liks between our families.