The letters æ Æ are ligatures. You can add them to your font as explained in this tutorial.
Since the ão ligature has no standard Unicode mapping, add them to the Private Use Area. They will also need unique postscript names, e.g. “ao” and “AO”. I can easily do that for you to get you started if you attach your font to the forum. How many ligatures do you need?
There are several examples of scripts in the OpenType tutorial thread. Here is a very simple script for adding just two ligatures to your font:
#input "Your Font Name.ttf"
#output "Your Font Name.otf"
script latn {
feature ligatures;
}
feature ligatures liga {
lookup ligaSub;
}
lookup ligaSub {
sub a o -> ao;
sub A O -> AO;
}
The OpenType Compiler (direct download link) is a command line program that runs in a DOS window. It reads your text file (the “script”), opens the font “Your Font Name.ttf” as defined in the script, and writes a new OpenType font called “Your Font Name.otf” in the same folder.
Create a new folder, let’s use C:\TEMP\ for now, and save the OTComp.exe in that folder, save the plain text file script in that folder as “Your Font Name.txt” (lets call it linck.txt for this demonstration), save a copy of your Truetype font there too, and compile the OpenType font.
To open a DOS command line window, press the Windows key + R to open the Run dialogue, type CMD, and press enter. At the DOS command line, type cd \temp\ to change directory to where OTComp.exe and linck.txt are saved. Then enter this command on the command line:
OTComp linck.txt
When you press enter, the program will run and compile the new font using your script. If there are any syntax errors in the text file, or if it cannot find your font, it will report an error.