Hello Jaime,
That thread is a great find. That sounds just like your data set, and I really like Luca's suggestion about how to add Sanger regions to an existing database. This step is important to mention: "restrict the Sanger sequences to the section amplified in the Illumina run"
Yes! When you are ready to try database building, make sure to check out the RESCRIPt plugin
Depending on your timeline and scope of work for this project, it might be easier/faster to present the amplicon analysis and Sanger sequences as two complementary ways to measure the host microbes. Seamless integration might be a big lift, but you can still present them side by side in the context of a paper.