PowerShell Multiple DynamicParam

I'm attempting to create a function for a script module that verifies the previous parameter has been set before it shows the next parameter.

The parameters I need are Identity, Share and Quota. I always want Identity to show, I don't want Share to show until the Identity has been set and I don't want Quota to show until the Share has been set.

I'm able to easily access $Identity, I'm not able to access $Share from within DynamicParam{}. I stepped through the script using PowerGUI and I was only able to see $Share when I hit Begin{}.

I have a way to workaround this by just showing Share/Quota if Identity is set, but ultimately I would like to learn how to keep adding additional parameters based on the previously set parameter.

A copy of the function is below. personfileutility.exe is just an executable we use to interact with the various systems to provision and gather information on a user.

function New-PersonalFiles
{
    [CmdletBinding()]
    Param
    (
        # Param1 help description
        [Parameter(Mandatory=$true)]
        $Identity
    )

    DynamicParam
        {
            $paramDictionary = new-object -Type System.Management.Automation.RuntimeDefinedParameterDictionary

            if (($Identity -notlike "") -or ($Identity -notlike $null)){
                $attributes = new-object System.Management.Automation.ParameterAttribute
                $attributes.ParameterSetName = "__AllParameterSets"
                $attributes.Mandatory = $true

                $lookup = [xml](\\servername\personalfiles\personfileutility.exe -a $Identity)

                $type = $lookup.User.user_directory.type.type

                if ($type -like "other" -or $type -like "staff") {
                    $arguments = @()
                    $arguments += "\\fileserver\sharename"
                }
                elseif ($type -like "faculty") {
                    $arguments = @()
                    $arguments += "\\fileserver\sharename"
                    $arguments += "\\fileserver\sharename2"

                }
                elseif ($type -like "student") {
                    $arguments = @()
                    $arguments += "\\fileserver2\sharename"
                }

                $ParamOptions = New-Object System.Management.Automation.ValidateSetAttribute -ArgumentList $arguments

                $attributeCollection = new-object -Type System.Collections.ObjectModel.Collection[System.Attribute]
                $attributeCollection.Add($attributes)
                $attributeCollection.Add($ParamOptions)


                $dynParam1 = new-object -Type System.Management.Automation.RuntimeDefinedParameter("Share", [String], $attributeCollection)

                $paramDictionary.Add("Share", $dynParam1)
            }

            if (($Share -like "\\fileserver\*"))
            {
                $attributes2 = new-object System.Management.Automation.ParameterAttribute
                $attributes2.ParameterSetName = "__AllParameterSets"
                $attributes2.Mandatory = $true

                $lookup = [xml](\\servername\personalfiles\personfileutility.exe -a $Identity)

                $type = $lookup.User.user_directory.type.type

                if ($type -like "other" -or $type -like "staff") {
                    $arguments = @()
                    $arguments += "15GB"
                    $arguments += "20GB"
                }
                elseif ($type -like "faculty") {
                    $arguments = @()
                    $arguments += "10GB"
                    $arguments += "15GB"

                }
                elseif ($type -like "student") {
                    $arguments = @()
                    $arguments += "5GB"
                    $arguments += "10GB"
                }

                $ParamOptions2 = New-Object System.Management.Automation.ValidateSetAttribute -ArgumentList $arguments2

                $attributeCollection2 = new-object -Type System.Collections.ObjectModel.Collection[System.Attribute]
                $attributeCollection2.Add($attributes2)
                $attributeCollection2.Add($ParamOptions2)


                $dynParam2 = new-object -Type System.Management.Automation.RuntimeDefinedParameter("Quota", [String], $attributeCollection2)

                $paramDictionary.Add("Quota", $dynParam2)
            }

            return $paramDictionary
        }

    <#
    .Synopsis
       Short description
    .DESCRIPTION
       Long description
    .EXAMPLE
       Example of how to use this cmdlet
    .EXAMPLE
       Another example of how to use this cmdlet
    #>

    Begin
    {
    }
    Process
    {
        \\servername\personalfiles\personfileutility.exe -a $Identity -c -q ((Invoke-Expression $PSBoundParameters.Quota)  / 1KB) -s $Share
    }
    End
    {
    }
}