Hello @Art_Miami ,
It looks like you already spoke with chat support about this issue. However, for the sake of visibility, I'll also post that insight here:
At this time, adding coding such as this isn't possible. There's a few different reasons for this, but the primary one is how we, by Compliance, have to be able to rewrite links for tracking purposes. This doesn't work with certain parameters, such as $ContactID and similar setups, and will simply result in them being overwritten / removed by our tracking rewrite.