Assuming that it is possible, I have been trying to substitute the Greek letters of my main font for those used in the math font. (if it works, it should look better on the page than what I have now.)
So, what have I missed/messed up in the following?
\definefontfamily[mainface][serif][Brill][
[protrusion=quality,
expansion=quality,
mode=node,
force=yes,
]
\definefallbackfamily[mainface][mm][TeX Gyre Pagella][preset=math:digitsnormal,features=f:oldstyle]
\definefallbackfamily[mainface][mm][Brill][range=0391-03A9,03B1-03C9]
\definefontfamily[mainface][mm][TeXGyre Termes Math]
\setupbodyfont[mainface,36pt]
\starttext
\emph{λ α μ β δ α}
\m{λαμβδα}
\stoptext
Alan