Soft error at order entry or Order in multiple of quantities

Hello,

Is it possible to throw a soft error if order is not in multiple of quantity.

Ex. 1) Item A needs to order in multiple of 3. Hence, sales order item line quantity should be 3\6\9\12 etc.

Ex. 2) Item B needs to order in multiple of 2. Hence, Sales order item line quantity should be 2\4\6\8 etc.

is it possible to throw error\warning if condition mentioned above are not matched ?

Also, if error\warning is not possible then can the sales order quantity be changed in multiples ?

(Ex. if Item A setup as multiple of 2, and if user enters the quantity as 1 in sales order then quantity should automatically change to 2)