I have an array that I had past help on and now I am attempting to modify that array. However, when doing so, parts of my "theorem" keep getting shifted to the next line.

Here is a MWE:

```
\documentclass{article}
\usepackage{amsmath,array}% http://ctan.org/pkg/{amsmath,array}
\newcommand{\twolinebrace}{\rlap{$\smash{\raisebox{.5\height}{\bigg\}}}$}}
\newlength{\LHS}\newlength{\RHS}
\newcolumntype{M}{>{$}p{\LHS}<{$}}
\newcolumntype{N}{>{$}p{\RHS}<{$}}
\begin{document}
\begin{theorem}
Let $\{A_{\alpha \colon \alpha \in A}\}$ and $\{B_{\beta \colon \beta \in  B}\}$ be families of subsets if a set $X$. Then:
\[
\renewcommand{\arraystretch}{1.1}
\begin{array}{@{}l@{\quad}l@{}}
\left.\kern-\nulldelimiterspace\\
             \begin{array}                                                                       {>{\bfseries}p{2em}@{\quad}M@{\quad$=$\quad}N}
  (a) & \big(\bigcup_{\alpha\in A} A_{\alpha}\big) \cup \big(\bigcup_{\beta\in B} B_{\beta}\big) & \bigcup_{(\alpha,\beta)} A_{\alpha} \cup B_{\beta}\\
  (b) & \bigg(\bigcap_{\alpha \in A A_{\alpha}} \bigg) \cap \bigg(\bigcap_{\beta \in B B_{\beta}} \bigg) &  \bigcap_{(\alpha,\beta)} A_{\alpha} \cap B_{\beta} 
\end{array}\right\} & {\text{Associative Laws}} \\
\left.\kern-\nulldelimiterspace\begin{array}{>{\bfseries}p{2em}@{\quad}M@{\quad$=$\quad}N}
  (c) & X \cup (Y \cup Z) & (X \cup Y) \cup Z \\
  (d) & X \cap (Y \cap Z) & (X \cap Y) \cap Z 
\end{array}\right\} & {\text{Associative Laws}} \\
\left.\kern-\nulldelimiterspace\begin{array}{>{\bfseries}p{2em}@{\quad}M@{\quad$=$\quad}N}
  (e) & X \cup (Y \cap Z) & (X \cup Y) \cap (X \cup Z) \\
  (f) & X \cap (Y \cup Z) & (X \cap Y) \cup (X \cap Z)
\end{array}\right\} & {\text{Distributive Laws}} \\
\end{array}
\]
\end{theorem}
\end{document}

```

I needed to add to my array, and now I am having additional problems. Now, the "text" 'Associative Laws', 'Distributive Laws', and 'de Morgan's Laws' are not being displayed correctly. Here is my latest MWE:

```
\documentclass{article}
\usepackage{amsmath,array}% http://ctan.org/pkg/{amsmath,array}
\newcommand{\twolinebrace}{\rlap{$\smash{\raisebox{.5\height}{\bigg\}}}$}}
\newlength{\LHS}\newlength{\RHS}
\newcolumntype{M}{>{$}p{\LHS}<{$}}
\newcolumntype{N}{>{$}p{\RHS}<{$}}
\begin{document}
\begin{theorem}
Let $\{A_{\alpha \colon \alpha \in A}\}$ and $\{B_{\beta \colon \beta \in  B}\}$ be families of subsets of a set~$X$. Then:
\[
\renewcommand{\arraystretch}{1.25}
\begin{array}{@{}l@{\quad}l@{}}
\left.\kern-\nulldelimiterspace\begin{array}{>{\bfseries}p{2em}@{\quad}M@{\quad$=$\quad}N}
(a) & X \cup Y &  Y \cup X \\
  (b) & X \cap Y &  X \cap Y
\end{array}\right\} & {\text{Commutative Laws}} \\
\left.\kern-\nulldelimiterspace\begin{array}{>{\bfseries}p{2em}@{\quad}M@{\quad$=$\quad}N}
(c) & X \cup (Y \cup Z) & (X \cup Y) \cup Z \\
  (d) & X \cap (Y \cap Z) & (X \cap Y) \cap Z 
\end{array}\right\} & {\text{Associative Laws}} \\
\left.\kern-\nulldelimiterspace\begin{array}{>{\bfseries}p{2em}@{\quad}M@{\quad$=$\quad}N}
(e) & X \cup (Y \cap Z) & (X \cup Y) \cap (X \cup Z) \\
  (f) & X \cap (Y \cup Z) & (X \cap Y) \cup (X \cap Z)
\end{array}\right\} & {\text{Distributive Laws}} \\
\end{array}
\]
\end{theorem}

```

Any additional help would be greatly appreciated in this matter.