custom/Functions.types.ps1xml

<?xml version="1.0" encoding="utf-8" ?>
<Types>
    <Type>
    <Name>Microsoft.Azure.PowerShell.Cmdlets.Functions.Models.Api20180201.Site</Name>
        <Members>
            <AliasProperty>
                <Name>Status</Name>
                <ReferencedMemberName>State</ReferencedMemberName>
            </AliasProperty>
            <AliasProperty>
                <Name>ResourceGroupName</Name>
                <ReferencedMemberName>ResourceGroup</ReferencedMemberName>
            </AliasProperty>
            <ScriptProperty>
            <Name>SubscriptionId</Name>
            <GetScriptBlock>($this.ServerFarmId -split "/")[2]</GetScriptBlock>
        </ScriptProperty>
        </Members>
    </Type>
    <Type>
    <Name>Microsoft.Azure.PowerShell.Cmdlets.Functions.Models.Api20180201.AppServicePlan</Name>
        <Members>
            <AliasProperty>
                <Name>ResourceGroupName</Name>
                <ReferencedMemberName>ResourceGroup</ReferencedMemberName>
            </AliasProperty>
            <ScriptProperty>
            <Name>SubscriptionId</Name>
            <GetScriptBlock>($this.Id -split "/")[2]</GetScriptBlock>
        </ScriptProperty>
        </Members>
    </Type>
</Types>