This is my preamble :
\documentclass[12pt,thmsa]{article}
\usepackage{natbib}
\usepackage{amsmath,amsfonts,amssymb,amsthm}
\usepackage{breqn}
\usepackage{rotating}
\usepackage{threeparttable}
\usepackage{booktabs}
\usepackage[para,multiple]{footmisc}
\usepackage{mathtools}
\begin{document}
First equation issue
\begin{flalign}
{w_1} &= \left\{N_1(-d_+(S_{dt},dt)+N_2(d_+(S_{dt},dt)),-d_+(S_{2dt},dt);-\rho_{12})+N_3(d_+(S_{dt},dt),d_+(S_{2dt},2dt),-d_+(S_{3dt},3dt);\rho_{12},-\rho_{13},-\rho_{23})...\right\},
\end{flalign}
\begin{flalign}
{w_2} &= \left\{N_1(-d_-(S_{dt},dt)+N_2(d_-(S_{dt},dt)),-d_-(S_{2dt},dt);-\rho_{12})+N_3(d_-(S_{dt},dt),d_-(S_{2dt},2dt),-d_-(S_{3dt},3dt);\rho_{12},-\rho_{13},-\rho_{23})+...\right\},
\end{flalign}
My second equation troubling me:
\begin{align}
&\varepsilon {B_t} \left\{ {1 - {e^{ - \delta (T - t)}}N( - {d_ + }(\varepsilon {B_t},K,T - t)) - \delta \int\limits_t^T {{e^{ - \delta (s-t)}}N( - {d_ + }(\varepsilon {B_t},{B_s},s - t))\;ds} } \right\} \\
&= K \left\{ {1 - {e^{ - r(T - t)}}N( - {d_ - }(\varepsilon {B_t},K,T - t)) - r\int\limits_t^T {{e^{ - \delta (s-t)}}N( - {d_ - }(\varepsilon {B_t},{B_s},s - t))} {\kern 1pt} \;ds} \right\}.
\end{align}
My third equation:
\begin{align}
P_3 = &Xe^{-rT/3}N_1[-d_-(B_{T/3},T/3)]-S_{T/3}N_1[-d_+(B_{T/3},T/3)]\nonumber\\
&+Xe^{-2rT/3}N_2[d_-(B_{T/3},T/3), -d_-(B_{2T/3},2T/3); -1/\sqrt{2}]\nonumber\\
&-S_{T/3, 2T/3}N_2[d_+(B_{T/3}, T/3),-d_+(B_{2T/3},2T/3);-1/\sqrt{2}]\nonumber\\
&+Xe^{-rT}N_3[d_+(B_{T/3},T/3), -d_+(B_{2T/3},2T/3), -d_+(X,T);1/\sqrt{2},-1/\sqrt{3},-\sqrt{2/3}]\nonumber\\
&-S_{T/3, 2T/3}N_3[d_-(B_{T/3},T/3),d_-(B_{2T/3},2T/3),-d_-(X,T);1/\sqrt{2},-1/\sqrt{3},-\sqrt{2/3}],
\end{align}
\\
to break the equations at sensible places. Also please fix the above example so it is a single document people can run to see the issue.