(a) If two or more commission merchants are employees or agents solely for one person, they may be covered by a single bond in an amount determined under Section 147.023 of this code on the basis of combined purchases and sales.
(b) Two or more commission merchants not subject to Subsection (a) of this section may be covered under a single bond in an amount not less than the aggregate amount of individual bonds required under Section 147.023 of this code.