Hints of NSIs from $D_{s}^{+}\rightarrow K^{+}\upsilon\bar{\upsilon}$, $D^{0}\rightarrow\pi^{0}\upsilon\bar{\upsilon}$ and $D_{s}^{+}\rightarrow D^{+}\upsilon\bar{\upsilon}$

We study rare decays [Formula: see text], [Formula: see text] and [Formula: see text] in NSIs. We calculate the NSIs branching ratios of these decays. There is a strong dependence of these on new physics parameter. We include second and third generation of quarks in the loop for these decays. We show that these provide stringent constraints on [Formula: see text], where Q = u, c, t, and [Formula: see text], where q = d, s, b. It is also pointed out that [Formula: see text] for α, β = e, μ.