I've been absent from the forums for a (short) bit, but long or short it's always hard to catch up on all the postings.

So I am not up-to-date on why Meghan's father's presence at the wedding is being questioned. Something to do with his health? But not sure why that got floated as a point of discussion.
Anyway, if the question regarding his presence is valid I think Prince Charles would be a great substitute.
I could be wrong (of course) but it's possible Meghan's mother may not want such a front-and-center role, either. I could see both parents declining and for very sensible reasons. Meghan may be entering the royal fish bowl, but they are definitely not. They are not British subjects, and have very modest and ordinary lives. They likely would want to support Meghan in every way but participating in this massive elevation in public status may not be anything they want to wrangle, and understandably. Meghan is making this choice for herself alone.
This is not to say her parents would not attend, just not choose to be part of the panoply. This is so far beyond walking one's daughter down the aisle at the village church. Neither parent is interested in the spotlight, that is clear. The wedding is pageantry for the masses, let it be within the confines of that world, with Prince Charles as the escort, leaving her parents the comfort of not having to 'perform'. Just some thoughts.