AT best, you get some 40 conversions down to 9mm. And, some 40 owners get conversion barrels to go from 40 to 357 sig, depending on the brand of gun and availability of the barrel.
You will not get a 9mm/40 to up convert to a 45. Not gonna happen. Slide, barrel and frame all have different dimensions. The body of the frame (grip) will also be bigger on a 45 caliber of the same gun model. Go look at some 9mms and 45 ACP models of the exact same model (like an HK UCP9 and HK USPc45). Not the same size grip.
EVen a 1911 in various calibers typically cannot just covert like that with a simple change of the slide. Ejectors, extractors, feed ramps, etc... All are slightly different in various calibers