Simphony 19.5+ - Adding tender with chargetip and reference via SIM or extensibility

[JimFromCanada]

I can't add a tender with gratuity and a reference string in Simphony 19.5+ via SIM or extensibility and have them be linked together / both make use of the reference string.

This seems like it should be such a simple thing so I am likely missing something super obvious.

A payment with gratuity can be applied via SIM in RES 3700 by calling 'MakeKeys' a few times. If you want a reference string and gratuity, you can set up the tender so that this can be added through keystrokes.
The general gist for RES 3700:

1. LoadKybdMacro Key(9, 999) // assuming tender media ID of 999
2. LoadKybdMacro MakeKeys(<amount>), @KEY_ENTER, MakeKeys(<gratuity/chargetip amount>), @KEY_ENTER
3. LoadKybdMacro MakeKeys(<reference string such as masked card number>), @KEY_ENTER

This would have the tender be applied to the check with a chargetip, and contain the reference string on both. It also links the chargetip to the tender so that if someone voids the tender, the chargetip can be voided with it.

Adding a tender with gratuity and references can also be done quite easily in STS2 by adding a new tender detail object to the check and ensuring it contains the chargetip (slight caveat with multiple payments on onecheck) and reference(s).

This seems impossible with the extensibility application method of doing things with Simphony 19.5+

How can this be accomplished with SIM in Simphony 19.5+? It seems like both SIM and "extensibility" suffer from the same limitation. I.e.: even if you attempt to apply a tender via an extensibility plug-in, it still uses the same underlying API calls and doesn't link a chargetip to the tender--the same issue SIM faces as it seems like a shared API / surface.
**
Edit: this is mostly concerning the scenario where you're applying more than 1 tender (payment) to a check. i.e: $10 check. 1 payment is for $5 plus $0.50 gratuity, the other payment is for $5 with gratuity of $1.00. There is seemingly no way to link the chargetips to the correct payment (i.e.: reference string, grouping them together, etc).