Thanks for your replies, I appreciate it very much.

I had the apprehension that it would be the way you wrote.

Since my parent simulation was run with all27_lipid I rather stick with this, shouldn't I?
If not, I'll see if we can purchase the latest CHARMM ;-) version when it got release to get my hands on the new forcefield files and avoid messing around with these.

Meanwhile I'll try to combine all27_prot_na and all27_lipid.

Thanks a lot!