You can ask for more, and I encourage you to do so. The first suggestion I shall make is that you choose how I dress for the wedding - I wish to indulge you on that day. In every way.

[Dimitri would be a good chose, though, if a king is not enough...]

Why not joint officiants? Dimitri shall serve as King in his own right, and I believe Byleth is at the head of a major religion of his world. Between the two of them, there shall be some legitimacy. Enough that none would argue else-wise.

[In their hearts they'd be married anyway, and that's all they would need. The bonding of their souls would be more than enough evidence.]

I shall craft it with more care than anything I have created - barring, perhaps, the crystal I once gifted you. That, you have my word. It will be my hope that you bear it with pride, and that I may be proud to have you seen wearing it.

The nature of this place means that even should we invite all inhabitants, it shall remain a relatively small function. Though...

[His voice grows slightly concerned.]

It is my nature to be incredibly social, and as such I have made many friends here. Would you find discomfort should I invite them all? It would be, I admit, much of the populace.