matt on 05 Mar, 2019 05:04 AM
Sorry for the delayed response, this slipped through the cracks.
To confirm, you're looking to create custom marker symbols? You can host them elsewhere and add them via a custom URL on the marker symbol dialog, or with a pro account, upload them directly to your account.
We're in the process of redoing the symbol set and have had a few requests like this lately, is there a single document listing the symbols you're trying to add? Incorporating some of them into the default set may be a possibility.