Full backups do not and never have affected the LSN chain for log backups in any way, means, guise or form (with the sole exception of the first full backup ever taken)
You can take as many full backups as you like, copy only or no copy only and they will not affect the LSN chain at all.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability