I want to use refining loop option to build missing residues for my target protein. First I get the FASTA file structure of protein then I load it into Chimera, after that in the Structure tab I select load structure, then I see the protein. After that Again in the "Structure" tab I select Modeller(loops/refinement). The rest is easy for creating the new structure PDB. But the problem is that I want whole protein to be treated in this refinement, but it only chose one chain, How can I do this for both chains at once?