[NTG-context] merging data from four files in one document

Hi all, I try to merge data from four files in one document. The source files are simple text files, each with 420 numbered lines of text. I have created a simple natural table with cells for the different pieces of data. I would like to make one document with 420 tables, each with the right data from the four source files (so Table 1 with data from line 1 from file One and line 1 from file Two and line 1 from file Three and line 1 from file Four, and next Table 2 with data from line 2 from file One and line 2 from file Two et cetera...) What is the best way to automate this process? Thanks, Jelle