When customers will not be taking the merchandise with them and make a deposit to hold the item, the sale is recorded on the system as a Layaway Sale.
Custom work and repairs are entered in the layaway sale screen. This type of sale is similar to a layaway in that the customer will not be paying for the service right away. (they may not be making any payment up front.)
If you want to make a record of when a customer makes an additional payment on a layaway sale, the sale must have previously been entered on the system. So if you have a number of outstanding layaways, you should probably enter them all in so that it will be easy for you to properly record subsequent layaway payments.