Combining unique data in fields from multiple records that are similar

[Vic]

I'm a novice and need a little help I have a table that
has the following
Model Option Serial OptMix
A 123
A 001 123
A 002 123
A 004 123
A 223
A 010 223
B 321
B 022 321

and so on...

I'm trying to update the OptMix field so the table looks
like this:
Model Option Serial OptMix
A 123 001, 002, 004
A 001 123 001, 002, 004
A 002 123 001, 002, 004
A 004 123 001, 002, 004
A 223 010
A 010 223 010
B 321 022
B 022 321 022

I did find Microsoft's help file 322813 for combining
childrecords. It works to an extent, however it takes
every option in the table and combines them for every
record Example: 001, 002, 004, 010, 022 ... etc

Is there any code that would collect and combine the
options until the serial changes and then move onto the
next serial. I've been trying to modify the code and query
in Microsoft's help file and havEn't been successful.

Thanks Any Help,

V