You should be able to run this script against the system and company databases for Dynamics GP and find the foreign keys in what tables.
I don't know that we have any documentation with FK information. If we did, it would be the SDKs, which we haven't put out a new one since probably GP 2016 or so.
The FK script is this:
SELECT
FK_Table = FK.TABLE_NAME,
FK_Column = CU.COLUMN_NAME,
PK_Table = PK.TABLE_NAME,
PK_Column = PT.COLUMN_NAME,
Constraint_Name = C.CONSTRAINT_NAME
FROM
INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS C
INNER JOIN
INFORMATION_SCHEMA.TABLE_CONSTRAINTS FK
ON C.CONSTRAINT_NAME = FK.CONSTRAINT_NAME
INNER JOIN
INFORMATION_SCHEMA.TABLE_CONSTRAINTS PK
ON C.UNIQUE_CONSTRAINT_NAME = PK.CONSTRAINT_NAME
INNER JOIN
INFORMATION_SCHEMA.KEY_COLUMN_USAGE CU
ON C.CONSTRAINT_NAME = CU.CONSTRAINT_NAME
INNER JOIN
(
SELECT
i1.TABLE_NAME, i2.COLUMN_NAME
FROM
INFORMATION_SCHEMA.TABLE_CONSTRAINTS i1
INNER JOIN
INFORMATION_SCHEMA.KEY_COLUMN_USAGE i2
ON i1.CONSTRAINT_NAME = i2.CONSTRAINT_NAME
WHERE i1.CONSTRAINT_TYPE = 'PRIMARY KEY'
) PT
ON PT.TABLE_NAME = PK.TABLE_NAME
-- optional:
ORDER BY
1,2,3,4
Thanks