Moneylab has a create your own category feature that allows you to create your own sub-category within any category group.
If you are considering using custom categories you might also find transaction Tagging useful. Tagging allows you to define your own Tags and apply those tags to transactions in any category. You can use transaction Tags to analyse your spending across Categories. You might use transaction tags to track things like tax-deductible expenses or the expenses related to a specific project like a home renovation or a holiday.
You can find the create your own category feature in the Categorise page. The Add Category link is available under each Category group, when you select a Category group from the Categorise page.
You will see it under the list of subcategories within the Category group.
Select the link and type in a name for your new category and click the green tick icon to save your new subcategory.
You can also edit or delete any of your own subcategories by selecting the pencil icon (Edit) or selecting the red cross icon (Delete).