How to create a symbol in EAGLE that consists of multiple other symbols?
Several things:


there's a package and there's a symbol. Package exists to connect pads on the board with conductive tracks, symbol on schematic exists to present, in human readable format, the sense of the connections. I saw many times people using package-like symbols on schematics, and it is not a right way - it creates messy circuit diagrams which are hard to read. My advice: do not draw symbol as it is shown in this datasheet;
then, you can see there're two identical functionally independent pieces in this package. You should create a symbol for one of them, and then, at device level, add two of them to the device, and then assign package and pins to pads of the symbol;
there's a trick. I am sure there's LED symbol already existing in DIODE library, and I am sure there's MOSFET existing in some other library. You do not need to reinvent bicycle, your task is to copy-paste their symbols into newly created symbol, and ensure pins are named properly, and symbol in overall looks properly and is human-readable.


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