William does not automatically becomes Prince of Wales. Charles has to make him Prince of Wales.
He does become Duke of Cornwall and Duke of Rothesay when Charles becomes King.
Fat chance that Charles won't make William Prince of Wales when the appropriate time arrives, which btw, I'm sure none of the royals are exactly looking forward to.
Oh boy with Meghan's Dad and half-siblings. They apparently can not stand seeing Meghan receiving all of this attention on the world stage. Wowza! This is beyond idiotic this point by Meghan's Dad. How relieved Meghan must be that the press were unable to locate her Dad in Mexico until some time after the engagement had already been announced.

I think sobster Samantha (formerly Yvonne Markle) is behind all this putting nonsense into her Dad's head. I can't see Markle Sr. being the one coming up with complaints about the clothes Meghan is wearing?!
I wonder whether it might have even helped had Meghan went quietly on a trip to Mexico incognito during the dating period before there was a ton of attention being paid to gauge her Dad's state of mind and try to placate him, in advance of an engagement announcement. I think Meghan and Harry knew they were heading for marriage almost from the beginning of their relationship. In the end, I suspect Meghan was trying to let sleeping dogs lay low for as long as possible. Both she and Harry had a ton of good reasons for wanting to guard their privacy in the early getting to kno each other stage of their relationship.
I get the impression that the whining older upstart half siblings became more bitter and jealous once Meghan attained success with
Suits in Toronto. But back then, she was still only an increasingly successful actor on a cable tv series that was doing well, but still was not a prevalent topic of conversation worldwide. So no one cared about any of the cast's family backgrounds, and Meghan always spun positivity about her parents and her upbringing on her Instagram. Once Prince Harry entered the picture and the relationship secret was out, it was game over. Samantha began the bitter jealousy charge forthwith, aided and abetted by the reprehensible tabloid media.
Apparently, the lowly media will continue to wring whatever they can out of the terrible Markles:
ET
https://www.youtube.com/watch?v=idIy7Tuw54o 
Yep, Meghan surely isn't happy about all these old childhood photos being so widely released to the public! My goodness!
ABC
https://www.youtube.com/watch?v=vxaOX9-WSy8 (interesting comments by Omid Mio Scobie, royal reporter)
Some royal observers have had enough:
https://www.thedailybeast.com/its-time-to-stop-the-classist-sexist-attacks-on-meghan-markle
https://www.refinery29.com/2018/07/204402/thomas-markle-meghan-looks-scared-royal-duties
https://jezebel.com/meghan-markle-s-dad-is-really-bumming-me-out-these-days-1827623578
Tom Markle:
"The phone number I had for her no longer works... I have no way of reaching my daughter..." 
And by this point, you never will!