How to keep the exponent in the same place after adding marks above variables?

Question

If I add a grave (using \grave{}) or a tilde (using \widetilde{}) above a variable, the position of the exponent stays the same as if the grave or tilde were not being used. However, if I use both at once, the exponent changes positions.

Here is a minimum working example showing the issue.

\documentclass[a4paper]{article} 
\usepackage{amsmath} 
\begin{document}
\begin{equation}
    \mathbf{B}^{T} \mathbf{A}^{-1} \mathbf{B}
\end{equation}
\begin{equation}
    \mathbf{B}^{T} \widetilde{\mathbf{A}}^{-1} \mathbf{B}
\end{equation}
\begin{equation}
    \mathbf{B}^{T} \grave{\mathbf{A}}^{-1} \mathbf{B}
\end{equation}
\begin{equation}
    \mathbf{B}^{T} \grave{\widetilde{\mathbf{A}}}^{-1} \mathbf{B}
\end{equation}
\end{document}

How can I use both without changing the position of the exponent?

Answer 1

You can use a double {} see the code below and the output. All the exponents are to the same height.

\documentclass[a4paper]{article} 
\usepackage{amsmath} 
\begin{document}
\begin{equation}
    \mathbf{B}^{T} \mathbf{A}^{-1} \mathbf{B}
\end{equation}
\begin{equation}
    \mathbf{B}^{T} \widetilde{\mathbf{A}}{}^{-1} \mathbf{B}
\end{equation}
\begin{equation}
    \mathbf{B}^{T} \grave{\mathbf{A}}^{-1} \mathbf{B}
\end{equation}
\begin{equation}
    \mathbf{B}^{T} \grave{\widetilde{\mathbf{A}}}{}^{-1} \mathbf{B}
\end{equation}
\end{document}