# Adding new ligatures to an overleaf-document

I'm currently transcribing some old books using overleaf as my compiler of choice. I wanted to copy some old ligatures (æ, œ, ct, ...).

I have already read some questions, (e.g. How add my own ligature) where it's been said to use the fontspec-package (and XeTeX, of course) and include another mapping. Unlucky, this doesn't work out on overleaf (or I failed myself) and now I'm wondering, whether there is another way to do so.

\documentclass[11pt, doublespacing]{book}
\usepackage{fontenc}
\usepackage[greek, latin]{babel}
\usepackage{alphabeta}
\input{preamble} %(nothing too important)

\usepackage{fontspec}[Mapping=ligaturae.map]

\begin{document}

...

\end{document}


I actually copied the map-file from the guide above (How add my own ligature) and added changed two lines to the custom ligatures I wanted

; additions by me
U+0061 U+0065   <>  U+00E6  ; ae -> æ
U+006F U+0065   <>  U+0153  ; oe -> œ

• Welcome to TeX.SE... Can you provide more details (regarding what font used, etc.) with a MWE? – MadyYuvi Sep 28 '20 at 13:39
• I added some details. regarding fonts: I prefer the 'classic' LaTeX-font, TNR, I suppose, but if there are better/easier ones, I'll change. – Aureius Sep 28 '20 at 14:34
• For many fonts, this is Ligatures=Rare or Ligatures=Historic. – Davislor Sep 28 '20 at 17:48
• Latin Modern doesn’t have the ct; you need to find a font that has what you want, then ask how to use it, because the method will depend on how the font’s features were defined. – Thérèse Sep 28 '20 at 18:48
• I don’t know of a language in which all occurrences of ae and oe become æ and œ (even in French, spelling a word with œ is sometimes incorrect); in my opinion, it would be easier to type æ and œ directly where appropriate than to create a font feature and turn it on or off as needed. This is possible because — unlike some ligatures — æ and œ are in Unicode. – Thérèse Sep 29 '20 at 11:29