If you have a customer who has a Quarterly and a Monthly service, and you want to arrange it so the Quarterly and Monthly are on the same day and time, create the series so the Quarterly has both the Quarterly and the Monthly services, and create a Seasonal series of 8 months, skipping the months with the Quarterly.

For example: Your Quarterly visit is January, April, July, and October on the first Thursday of the month. You want your Monthly to be also on the first Thursday.

Create the Quarterly as usual with both the Quarterly Residential and Monthly Residential as the services.

Remember on the Schedule tab that the week of the month and day of the week must match the first service date; otherwise, you'll have two services that first month.
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This is how the Quarterly series looks in the customers' Work Orders tab.

For the Monthly service create a new series and add the Monthly service on the Billing tab.

On the Schedule tab, instead of using the Monthly service frequency, use Seasonal and select the months not included in the Quarterly.

This is how the Seasonal series (bottom) looks in the customers' Work Orders tab. Notice the Quarterly series (top) has April and July scheduled, and April and July are not scheduled in the Seasonal.

See also How to create a Quarterly Work Order Series

See also How to create a Seasonal Work Order Series