  The emergence of active regions (ARs) leads to various dynamic activities.
Using high-resolution and long-lasting H$\alpha$ observations from the New
Vacuum Solar Telescope, we report the dynamics of NOAA AR 12700 in its emerging
phase on 26 February 2018 in detail. In this AR, constant interchange
reconnections between emerging fibrils and preexisting ones were detected.
Driven by the flux emergence, small-scale fibrils observed in H$\alpha$
wavelength continuously emerged at the center of the AR and reconnected with
the ambient preexisting fibrils, forming new longer fibrils. We investigate
three scenarios of such interchange reconnection in two hours. Specially, the
third scenario of reconnection resulted in the formation of longer fibrils that
show pronounced rotation motion. To derive the evolution of the magnetic
structure during the reconnections, we perform nonlinear force-free field
extrapolations. The extrapolated three-dimensional magnetic fields clearly
depict a set of almost potential emerging loops, two preexisting flux ropes at
03:00 UT before the second reconnection scenario, and a set of newly formed
loops with less twist at 03:48 UT after the third reconnection scenario. All of
these extrapolated structures are consistent with the fibrils detected in
H$\alpha$ wavelength. The aforementioned observations and extrapolation results
suggest that the constant interchange reconnections resulted in that the
magnetic twist was redistributed from preexisting flux ropes towards the
newly-formed system with longer magnetic structure and weaker twist.
