Custom circuit string definition

Hi!
I would like to try fitting my spectra with the following TL:

<img width="368" height="133" alt="Image" src="https://github.com/user-attachments/assets/f6b1fd5b-60f0-4224-9a09-39b196f9df4a" />

However, I am not sure how to express the Ca, Cb, ... capacitors in the library's notation to write the custom circuit string. What would the right circuit string look like?

Thanks!