Multiple UI++ in task sequence

Shouldn't need to call a completely separate UI++. Just use conditions to either display a specific action or use something like a switch statement to only show the appropriate options depending on the previous selection.

Lots of ways to do this, but this one is probably the most simple to get started with. This will display a country selection. Then, using conditions, it will only display one of the Location prompts.

<Action Type="Input" Name="Country" Title="Select a Country">
<ChoiceInput Variable="CountrySelection" Question="Select the country this computer will exist in." >
<Choice Option="United Kingdom" Value="UK"/>
<Choice Option="Denmark" Value="DK"/>
</ChoiceInput>
</Action>

<Action Type="Input" Name="Location" Title="Select UK Location" Condition='"%CountrySelection%" = "UK"'>
<ChoiceInput Variable="LocationSelection" Question="Choose a location in the United Kingdom" Default="No" Required="True" >
<Choice Option="London" Value="London"/>
<Choice Option="Birmingham" Value="Birmingham"/>
<Choice Option="Liverpool" Value="Liverpool"/>
</ChoiceInput>
</Action>

<Action Type="Input" Name="Location" Title="Select DK Location" Condition='"%CountrySelection%" = "DK"'>
<ChoiceInput Variable="LocationSelection" Question="Choose a location in Denmark" Default="No" Required="True" >
<Choice Option="Copenhagen" Value="Copenhagen"/>
<Choice Option="Arhus" Value="Arhus"/>
<Choice Option="Odense" Value="Odense"/>
</ChoiceInput>
</Action>

Again, many ways to do this that are less code and more efficient. Specifically, I would be using the ChoiceList feature to populate your choices with a single variable, then use a SWITCH action to populate that ChoiceList variable depending on the first question. Then you'd only need one location question that would automatically change values using the variables. But that's 2.0 stuff for ya to work on.