  Penumbral transient brightening events have been attributed to magnetic
reconnection episodes occurring in the low corona. We investigated the trigger
mechanism of these events in active region NOAA 12546 by using multi-wavelength
observations obtained with the Interferometric Bidimensional Spectrometer
(IBIS), by the \textit{Solar Dynamics Observatory} (SDO), the \textit{Interface
Region Imaging Spectrograph} (IRIS), and the \textit{Hinode} satellites. We
focused on the evolution of an area of the penumbra adjacent to two small-scale
emerging flux regions (EFRs), which manifested three brightening events
detected from the chromosphere to the corona. Two of these events correspond to
B-class flares. The same region showed short-lived moving magnetic features
(MMFs) that streamed out from the penumbra. In the photosphere, the EFRs led to
small-scale penumbral changes associated with a counter-Evershed flow and to a
reconfiguration of the magnetic fields in the moat. The brightening events had
one of the footpoints embedded in the penumbra and seemed to result from the
distinctive interplay between the pre-existing penumbral fields, MMFs, and the
EFRs. The \textit{IRIS} spectra measured therein reveal enhanced temperature
and asymmetries in spectral lines, suggestive of event triggering at different
height in the atmosphere. Specifically, the blue asymmetry noted in \ion{C}{2}
and \ion{Mg}{2} h\&k lines suggests the occurrence of chromospheric evaporation
at the footpoint located in the penumbra as a consequence of magnetic
reconnection process at higher atmospheric heigths.
