First, create your first server ui form with ModalForm, ActionForm, or MessageForm.
// pseudocode
new ModalFormData()
Show the form to the player with show function with a callback.
// pseudocode
let player: Player;
new ModalFormData().show(player).then((response) => {
// callback code
});
In the callback call another form, it can be any of the three forms.
// pseudocode
let player: Player;
new ModalFormData().show(player).then((response) => {
new ActionFormData().show(player);
});