Thanks, Mikael. That works nicely. Note: I changed

\definefallbackfamily [mainface] [mm] [Brill] [preset=math:
lowercasegreeknormal]

to

\definefallbackfamily [mainface] [mm] [Brill]
[preset=math:uppercasegreeknormal],
since Knuth/TeX sets Greek capital letters upright.

Alan

On Thu, Mar 10, 2016 at 9:56 AM, Mikael P. Sundqvist <mickep@gmail.com>
wrote:

> On Thu, Mar 10, 2016 at 3:34 PM, Alan Bowen <bowenalan03@gmail.com> wrote:
> > 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}
> >
> > 0123456780
> >
> > \m{0123456780}
> >
> >
> > \stoptext
> >
> > Alan
> >
> >
> ___________________________________________________________________________________
> > If your question is of interest to others as well, please add an entry to
> > the Wiki!
> >
> > maillist : ntg-context@ntg.nl /
> > http://www.ntg.nl/mailman/listinfo/ntg-context
> > webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
> > archive  : http://foundry.supelec.fr/projects/contextrev/
> > wiki     : http://contextgarden.net
> >
> ___________________________________________________________________________________
>
> What if you change
>
> \definefallbackfamily[mainface][mm][Brill][range=0391-03A9,03B1-03C9]
>
> to
>
> \definefallbackfamily [mainface] [mm] [Brill]
> [preset=math:lowercasegreeknormal]
> \definefallbackfamily [mainface] [mm] [Brill]
> [preset=math:lowercasegreekitalic]
>
> That seems to work here with your example. By the way, I have not seen
> the Brill font before. It was very nice!
>
> /Mikael
>
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to
> the Wiki!
>
> maillist : ntg-context@ntg.nl /
> http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
> archive  : http://foundry.supelec.fr/projects/contextrev/
> wiki     : http://contextgarden.net
>
> ___________________________________________________________________________________