This page summarizes the general techniques for performing a taxonomic lump in Avisys. There are two kinds of lump; one where a species is lumped into an existing species, and one where two or more species are lumped into an entirely new species. We'll use the lump of Pale-billed Firefinch into African Firefinch as an example of the first kind of lump, and the lump of Eurasian Reed Warbler and African Reed Warbler into Common Reed Warbler as an example of the second kind of lump.
Of course, you don't need to do anything at all if you have no sightings of the lumped species, so we'll assume here that you have sightings of Pale-billed Firefinch and one or both of Eurasian Reed Warbler or African Reed Warbler.
First, you need to move all of your sightings of the lumped species to the species that will exist after the taxonomy update. For Pale-billed Firefinch, first click on African Firefinch to highlight its name, then either press Ctrl-F3, or equivalently click Utilities->Save Species for Edit. Either way, this will bring up a "Saved Species" dialog listing African Firefinch. Just click OK here. Then do a List Records of all of your sightings of Pale-billed Firefinch. Click on the first sighting, then on Edit, then on Species, then on African Firefinch, and finally on OK and Finished. You've now moved this sighting from Pale-billed Firefinch to African Firefinch. If you have a second sighting, highlight it and press enter, and then choose Yes for the question "Do you want to do mass modifys?", and then simply press enter on each subsequent sighting to perform the rename.
If you have sightings of them, you can do a corresponding procedure for each of Eurasian Reed Warbler and African Reed Warbler; however because these are going to a new species instead of an existing species, you can take a shortcut of just renaming the first species. For example, if you have seen African Reed Warbler you can simply rename that species to Common Reed Warbler. To rename a species, highlight its name (by clicking on it), click on Edit->Edit Species/Family Name, change the name, and click OK. If you have seen only one of the species, you are then done. If you have seen both Eastern and Western Sunbird, after renaming one of the species you will need to move sightings of the other species to Common Reed Warbler using the same procedure as described above for Pale-billed Firefinch.
How to do this is described here.
For lumps, there is nothing more to do after running the taxonomic update.