To generate the selects you can choose between using your custom created object or by accessing via AJAX a server resource that returns a custom formatted JSON .
You can set up two user journeys: one when all your selects are pre-generated first one has filled in options and the rest of them will be empty. The other option is that each select is generated on the go (once a value in the previous select is filled in, a new select is created).
In the first case, the fixed number of selects is required and this is recommended to be used only when the number of selects that will be chained is fixed.
The second case is ideal when you have a variable number of selects (depending on the user’s choosen options a different number of total selects could be generated)
The user also has the option to fully customize all the selects, by enabling the “Custom Selects” option, which will generate an easy customizable list with all the select options.