Let me try again with fonts in the ConteXt distribution.

The aim is to substitute Pagella letters (roman and Greek) and numerals for those in Dejavu Math. It gets the numerals and the Greek capitals right but the rest (roman lower– and uppercase, and lowercase Greek) are still in Dejavu. How can I fix this? 

\definefontfamily[mainface][serif][TeX Gyre Pagella][]

\definefallbackfamily[mainface][mm][TeX Gyre Pagella]
[range={0030-0039, 0041-005A, 0061-0071, 0391-03A9, 03B1-03C9}, scale=1]

\definefallbackfamily [mainface] [mm] [TeXGyrePagella][preset=math:lowercasegreeknormal]
\definefallbackfamily [mainface] [mm] [TeXGyrePagellaItalic] [preset=math:lowercasegreekitalic]
\definefallbackfamily [mainface] [mm] [TeXGyrePagella] [preset=math:uppercasegreeknormal]
\definefallbackfamily [mainface] [mm] [TeXGyrePagellaItalic] [preset=math:uppercasegreekitalic]


\definefontfamily[mainface][mm][Dejavu Math][scale=1]

\setupmathematics[autopunctuation={all}, ucgreek=normal, lcgreek=italic]

\setupbodyfont[mainface,10pt]

\starttext

A~B~C~a~b~c (Pagella)

\emph{A~B~C~a~b~c} (Pagella)\\
\m{A~B~C~a~b~c} (math: Pagella?)
\blank
0123456789 (Pagella) \\
\m{0123456789} (math: Pagella?)
\blank
δ \emph{δ} (Pagella) \\ 
\m{δ} (math: Pagella?)
\blank
π \emph{π} (Pagella) \\
\m{π} (math: Pagella?)
\blank
Π \emph{ Π} (Pagella) \\
\m{Π} (math: Pagella?)
\blank
Δ \emph{ Δ} (Pagella) \\
\m{Δ}  (math: Pagella?)

\stoptext

Alan

On Tue, Sep 5, 2017 at 5:42 PM, Alan Bowen <bowenalan03@gmail.com> wrote:
I should like to have the Brill font substitute for the Greek alphabet (upper and lower cases) as well for the numerals in Tex Gyre Termes Math. 

So far, I have been able to get the Brill numerals (oldstyle) but nothing more: the Greek letters in math mode are from Termes Math.

Here is what I have:

\definefontfamily[mainface][serif][Brill]
[protrusion=quality,
expansion=quality, 
mode=node,
force=yes,
]

\definefallbackfamily[mainface][mm][Brill][range={0030-0039, 0391-03A9, 03B1-03C9}, scale=1]

\definefallbackfamily [mainface] [mm] [Brill] [preset=math:lowercasegreeknormal]
\definefallbackfamily [mainface] [mm] [BrillItalic] [preset=math:lowercasegreekitalic]
\definefallbackfamily [mainface] [mm] [Brill] [preset=math:uppercasegreeknormal]
\definefallbackfamily [mainface] [mm] [BrillItalic] [preset=math:uppercasegreekitalic]


\definefontfamily[mainface][mm][TeX Gyre Termes Math][scale=0.94]
\setupmathematics[autopunctuation={all}, ucgreek=normal, lcgreek=italic]

\setupbodyfont[mainface,10pt]

\starttext

A~B~C~a~b~c

\emph{A~B~C~a~b~c}\quad math: \m{A~B~C~a~b~c}

0123456789\quad math: \m{0123456789}

δ \emph{δ}\quad math: \m{δ}

π \emph{π}\quad math: \m{π}

Π \emph{ Π}\quad math: \m{Π}

\stoptext

Any suggestions or pointers will be most welcome.

Alan