multiple subequations same line with reference

I'm trying to write several equations on one line, include a label for each equation, and also be able to view the equation number for each equation. Is this possible? I've seen several related questions but not ever including all the things I need, and I can't seem to get it working.

Here are some relevant questions: Multiple subequation labels in one \ref

https://stackoverflow.com/questions/3328806/latex-multiple-equation-references-in-one

How to place and number 3 short equations in one line?

What I need is something like

 \begin{subequations}
\begin{align}
\pmb{u} = \pmb{u}_{b} \label{eq:UBCs_D1}
\end{align}
\begin{align}
\pmb{u} = \pmb{0} \label{eq:UBCs_D2}
\end{align}
\begin{align}
\pmb{u} = \text{periodic} \label{eq:UBCs_P2}
\end{align}
\end{subequations}


Where all the equations (and their numbering) appear on the same line.

Any help is greatly appreciated.

 \noindent
$$\pmb{u} = \pmb{u}_{b} \label{eq:UBCs_D100}$$ &
$$\pmb{u} = \pmb{0} \label{eq:UBCs_D200}$$
$$\frac{\partial \pmb{u}}{\partial n} = 0 \label{eq:UBCs_N00}$$ &
$$\pmb{u} = \text{periodic} \label{eq:UBCs_P200}$$