How to combine two LED indicators (one to VCC, one to GND)
If you do not mind two transistors then the general principle implements
A OR NOT(B) at the LED Cathode. 

The circuit below should work with both inputs as logic level signals with not enough drive for an LED (or with "full power" signals such as you have".)

A low turns Q1 on  via R2.
R1 holds Q2 off if A is high and B is low as the base of Q2 would otherwise be floating -  which is not good design practice and can lead to partial turn on of transistor due to leakage currents. Similarly Q1 may benefit from a high value resistor (say 100K ) from base to V+ IF input A is high impedance when not low to enable LED. 







simulate this circuit &ndash; Schematic created using CircuitLab

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Either can be used to drive the LED directly (as now) with the other inverted to match.
eg here A could be connected to the collector of Q2 via a diode and R4 and Q1 omitted.
Thusly:

D2 may not be needed depending on impedance of B when not on.

A low and/or B high turn on LED.