If you need to add a new unit type (parent unit) before adding a new sub-unit then follow this guide on Units.
A sub-unit is a way of creating multiple copies of the same kind of rentable thing (a unit). Subunits are typically used in camping or touring parks for individual pitches – but can be used for fixed lodges, caravans and other properties wherever the rules for each sub-unit remain broadly the same as the parent unit.
Please note: a sub-unit will always look at the settings and rates on the PARENT UNIT, unless you override them on the sub-unit level. So, if you want all your subunits to inherit the settings you’ve put on the parent unit, just keep all the subunit settings set at zero.
In particular, the available date range of all subunits under a unit need to be the same.
However, maximum / minimum occupancy and pricing can differ from subunit to subunit.
If you put pricing in at the sub unit level to override that of the parent unit, the parent unit still needs to hold some price value, so that availability on that unit remains active.