Once a Contract has had any billing against it, the Next Bill On Day and Frequency are locked. This is to protect the Billing process against errors caused when a period is changed.
A change of date is essentially a change in the contract agreement you had with the customer. Therefore, the contract should be finished and a new one created.
To achieve this, from the master contract, edit and add .OLD as a suffix to the contract number if it represents a significant number for you. If you allow Jim2 system generated numbers, this step is not required. Save.
Select Create Similar.
When the options appear, make careful selections. It is important to select FINISH Copied Child Contracts.
It is strongly recommended to select Create Contract End Reads for the old contracts and Create Contract Start Reads for the new contract, along with most other fields.
Click OK to the first warning.
The second window confirms all the child contracts you are going to create copies of. Click OK.
A Create Contract End Read window will be presented.
Selecting the Billed Using Normal Read option is safest. However, you could use Auto Selected Reads, but this can cause an issue in the first invoice after this process.
Then select Submit Read.
A Create Contract Start Read window will be presented.
Select the Contract End Reads created in the previous step.
You will now be presented with the new master contract. Edit and update the Contract# to be the same as the .OLD version above.
Further information
How to