Differential expression pattern of known miRNAs

Question

[Rey]

Hi all, I am naive in sRNA-seq data analysis. I mapped my sRNA-seq data to mature and precursor plant miRNAs from miRBase. Now I want to study the expression patterns of these miRNAs across different samples.

1. For some miRNAs, only precursors have been identified. Can I use their mature sequences instead of precursor for differential expression analysis?
2. only mature miRNAs are used for differential expression analysis? as for some miRNAs, both mature and precursor were detecetd.
3. In my list, for example, the sequence of aof-miR167a and ata-miR167e-5p is the same. Could I include all miRNAs in the final file for differential analysis? or I should only use one of them?