Summary: We study positive solutions to singular boundary value problems of the form: \[\begin{cases} -u'' = h(t) \frac{f(u)}{u^\alpha} \quad \text{for } t \in (0,1), \\ u(0) = 0, \\ u'(1) + c(u(1)) u(1) = 0, \end{cases}\] where \(0< \alpha< 1, h \colon (0,1] \rightarrow (0,\infty)\) is continuous such that \(h(t)\leq d/t^\beta\) for some \(d> 0\) and \(\beta\in[0,1-\alpha)\) and \(c \colon [0,\infty) \rightarrow [0,\infty)\) is continuous such that \(c(s)s\) is nondecreasing. We assume that \(f \colon [0,\infty) \rightarrow(0,\infty)\) is continuously differentiable such that \([(f(s)-f(0))/s^\alpha]+\tau s\) is strictly increasing for some \(\tau\geq 0\) for \(s\in(0,\infty)\). When there exists a pair of sub-supersolutions \((\psi,\phi)\) such that \(0\leq \psi\leq\phi \), we first establish a minimal solution \(\underline u\) and a maximal solution \(\overline u\) in \([\psi,\phi]\). When there exist two pairs of sub-supersolutions \((\psi_1,\phi_1)\) and \((\psi_2,\phi_2)\) where \(0\leq \psi_1 \leq \psi_2 \leq \phi_1, \psi_1 \leq \phi_2 \leq \phi_1\) with \(\psi_2 \not \leq \phi_2\), and \(\psi_2, \phi_2\) are not solutions, we next establish the existence of at least three solutions \(u_1, u_2\) and \(u_3\) satisfying \(u_1\in [\psi_1,\phi_2], u_2\in [\psi_2,\phi_1]\) and \(u_3\in [\psi_1,\phi_1]\setminus ([\psi_1,\phi_2]\cup [\psi_2,\phi_1])\).