Here is some code to time align and splice (concatenate) different frequency lanes together. It is not fully verified yet, but works very well with my LOFAR offline converted test data in SIGPROC filterbank format.

Here is its GitHub repository.

Extending the code to handle PSRFITS and DADA files should be straightforward, but is left for a pull request for someone to write. ;-)

The use case is for when you have frequency lanes that have different starting times.