Question about 7-segment LED display modification

[locarazon]

I would like to modify the wiring and logic of a digital LED clock to:
1. adjust the numbers of LEDs per segment (3 LEDS per segment in some and 4 LEDs per segment in others) without lighting level
inconsistencies

2. Allow the new corner LEDs to be shared by the horizontal and vertical segments (so it lights up with either or both of the horizontal or vertical segments.) (again without light level inconsistencies).

Example: I want the upper right corner LED to light up for a "4" AND for a "5". Normally the segments are organized with a diagonal corner to avoid this problem but I am working with a strict grid.
The @ marks below are lit LEDS

@@@@-------@OO@
@OOO--------@OO@
@OOO--------@OO@
@@@@------@@@@
OOO @-------OOO@
OOO @-------OOO@
@@@@-------OOO@


We are using the standard clock IC SANYO's LM8560N AKA Texas Instruments's TMS3450NL AKA NTE's NTE2062 (specifications https://www.electro-tech-online.com/custompdfs/2004/05/nte2062.pdf) along
with Kingston L7104SRC/E (Super Bright Water Clear T1 Red LEDs:
specifications **broken link removed**).

The original wiring diagram is from a kit so I can't post it here but if you need it to answer the question I can send a link.

I will avoid the long tale of the various modifications I tried, but suffice to say, the LEDs lit up under bizarre circumstances (only one power line was attached to a segment--the other one was in the air but it still lights up) and it is time to ask for expert help.

Thanks,
locarazon

 

[Russlk]

Make the corner LED an 8th segment which lights up on the 2,3,4,5,7 & 8. You will have to make the logic for that seperatly, the standard 7 segment decoder will light the other LEDs.