Combine two Praat textgrid file

We have multiple people working on th开发者_如何学JAVAe same textgrid file and would like to combine it into a larger one. The textgird file has eight tiers. I would like to combine the textgrids files without messing up the tiers. I would like to do something like |x|- + -|x| into |x|x| for each of the eight tiers. Is it possible to do that? Thanks.