LaTeX 中双行双语段落的句子对齐

Question

我想一次翻译一个大文档的整个段落，并对齐新句子的开头。以下几乎是我想要做的，尽管它还没有对新句子进行对齐。

\documentclass{article}
\usepackage[margin=1in, paperwidth=8.5in, paperheight=11in]{geometry}
\usepackage[utf8]{inputenc}
\usepackage{url}
\usepackage{setspace}
\begin{document}

\def\english{In the heart of the forest lived three little pigs who were brothers. The wolf always was chasing them in order to eat them. In order to escape the wolf, the pigs decided to make a house each. The smallest made his from straw, to finish first and go out to play. The middle one constructed a cottage from wood. Seeing that his little brother had finished already, he hurried to go and play with him. The oldest worked on his house of brick. 'You'll soon see what the wolf does with your houses,' he scolded his brothers but they were having a great time.}

\def\spanish{En el corazón del bosque vivían tres cerditos que eran hermanos. El lobo siempre andaba persiguiéndoles para comérselos. Para escapar del lobo, los cerditos decidieron hacerse una casa. El pequeño la hizo de paja, para acabar antes y poder irse a jugar. El mediano construyó una casita de madera. Al ver que su hermano perqueño había terminado ya, se dio prisa para irse a jugar con él. El mayor trabajaba en su casa de ladrillo. - Ya veréis lo que hace el lobo con vuestras casas - riñó a sus hermanos mientras éstos se lo pasaban en grande.}

\begin{minipage}[t][0pt]{\linewidth}
    \setstretch{3}
    \english
\end{minipage}

\begin{minipage}[t]{\linewidth}
    \setstretch{3}
    \spanish
\end{minipage}

\end{document}

如何自动对齐新句子？对于奖励积分，我如何修改此方法以手动指示英语中的一个句子何时与西班牙语中的两个句子对齐？