I knew there had to be a simple way of doing this without digging deep into VB. My first combobox ie cmbPart_number, i have modified as follows - Row Source has all 3 fields in the SQL query ie SELECT part_number, part_name, EO_number from parts ORDER BY...;
I have modified the column count to 2 as Access always counts the first column in a table as number 0. So its Column 0,1 & 2 for all 3 fields. My column widths are 1";0"
Next I modified cmbPart_name's control source to read =cmbpart_number.column(1). Its row source has a SELECT statement SELECT part_number, part_name FROM parts, ORDER BY...
Column Count is 1 and Column Width is 0";1"
Finally for cmbEO_number, control source is =cmbpart_number.column(2). Row Source select statement is SELECT part_number, EO_number FROM parts ORDER BY...Column count is 1 and column width is 0";1"
This now works fine and any entry selected in the cmbPart_number box autopopulates the other 2.
Thank you all for your help.