Modelling phosphorylation sites in MDP

[chunhey]

Hello to the creators and contributors of CALVADOS.
First of all, thank you for your hard work for making such an amazing engine, I really enjoyed using CALVADOS.

I am currently trying to run a system that consists of proteins and RNAs with the proteins are modeled using MDP, and I'm wondering if it is possible to add phosphorylation sites to the MDP?
I tried modifying the residues csv file to incorporate the values of SEP and TPO from residues_pCALVADOS2.csv, then I modified the pdb by changing the target residues name from SER to SEP. I was hoping it will work but apparently the resname SEP is not recognised. Attached below is the error message I got:

Traceback (most recent call last):
File "/project/user/CALVADOS/examples/slab_IDR/PP12/run.py", line 16, in
sim.run(path=path,fconfig=fconfig,fcomponents=fcomponents)
File "/home/user/.conda/envs/calvados/lib/python3.10/site-packages/calvados/sim.py", line 648, in run
mysim.build_system()
File "/home/user/.conda/envs/calvados/lib/python3.10/site-packages/calvados/sim.py", line 149, in build_system
self.make_components()
File "/home/user/.conda/envs/calvados/lib/python3.10/site-packages/calvados/sim.py", line 87, in make_components
comp.calc_properties(pH=self.pH, verbose=self.verbose, comp_setup=comp_setup)
File "/home/user/.conda/envs/calvados/lib/python3.10/site-packages/calvados/components.py", line 171, in calc_properties
super().calc_properties(pH=pH, verbose=verbose)
File "/home/chsiuae/.conda/envs/calvados/lib/python3.10/site-packages/calvados/components.py", line 46, in calc_properties
self.calc_comp_seq()
File "/home/user/.conda/envs/calvados/lib/python3.10/site-packages/calvados/components.py", line 36, in calc_comp_seq
self.seq, self.n_termini, self.c_termini = seq_from_pdb(f'{self.pdb_folder}/{self.name}.pdb')
File "/home/chsiuae/.conda/envs/calvados/lib/python3.10/site-packages/calvados/sequence.py", line 58, in seq_from_pdb
res1 = convert_aa_code(res)
File "/home/user/.conda/envs/calvados/lib/python3.10/site-packages/MDAnalysis/lib/util.py", line 1447, in convert_aa_code
raise ValueError(errmsg) from None
ValueError: No conversion for SEP found (1 letter -> 3 letter or 3/4 letter -> 1 letter)

So I am out here looking for help or suggestions that would make this happen. Thank you all for your time in advance.