Can fighter jets be reloaded with ammunition mid-flight?
Aerial rearming has been a daydream of military tacticians for decades. However, the task is much more technically demanding than aerial refueling, which is in itself a fairly demanding task for pilot and boom operator just to get a 50-foot fuel hose hooked up.

The technical issues include:


Physically capturing and docking a smaller aircraft with a larger one. The USAF tried it back in the 50s with a B-36 carrying a specially-modified RF-84F. In those days there were no computerized flight controls, and docking the fighter back up with the mothership after it had done its thing proved to be more dangerous to the bomber than just running the mission without a fighter escort at all. It would not be inconceivable for modern avionics to improve on that, however the relative size of fighters compared to larger support craft has increased considerably. Here is a KC-135, built on the "Dash-80" airframe that also sired the 707, refueling an F-15C that's not really that much smaller when you look at it:


Placement of most ordinance under the aircraft. Most fighters and ground attack aircraft carry weapons on external hardpoints under the wings (the RAF-variant SEPECAT Jaguar being a notable example of both overwing pylons and the insanity of British aircraft designers):



When in refueling position under a tanker, the aircraft's most deadly weapons are on the wrong side of the jet to try to get to them to replace or reload them. You'd have to either bring the aircraft inside the mothership, or have it land on top (and provide a sheltered work area for a crew to get to the ordinance pylons).
Relative fuselage width of mothership versus wingspan of fighter. The largest fixed-wing craft in the U.S. arsenal is the C-5 Galaxy. It's a big plane (though not the biggest, that distinction belongs to the Ukrainians with the An-225). Here it is with a couple F-15s and a C-130 parked nearby for scale:



Even with a plane this size, able to transport other planes, you can see from the below photo that neither the F-14 being loaded nor the Galaxy is in a flight-ready condition at the time:



I'd be interested to see whether one of the light weight fighters (F-16, F/A-18) might fit with less disassembly (the F-18 might if you folded the wings), but it remains that you're just not going to be able to fly a modern fighter into another aircraft in midair, at least not with any currently-flying airframe combination.
Getting crew access to the plane. If you've ever seen a ground crew loading a fighter for a mission, you know it's a fairly complex process of not only putting the ordinance (which can weigh up to 2500 pounds for large laser-guided bombs) onto the hardpoints, but wiring up the arming and firing circuits for each one, and programming the plane's FCC with the loadout. This requires getting a lot of people underneath the aircraft (it can take two or three people to load one hardpoint especially if the ordinance has to be muscled into place; here's two people loading probably the lightest piece of external ordinance the USAF has onto an F-15C, and it's only two people because they're using a hydraulic loader):



As the aircraft can't be taken inside the mothership (see previous point), the only other possible place for this to be done is on top of the mothership. That means you'd have a crew out on top of the aircraft muscling ordinance into place. That first requires a sheltered area on top of the mothership that the fighter can be docked and tethered to, as there's no way a crew is getting anything done in a 150-knot headwind. The fuselage vs wingspan difference is important here too; you're not going to be loading AIM-9s onto the wingtips of an F-16 or F-18 when the F-16's wingspan is 33 feet while the cargo deck width (a stand-in for the amount of usable fuselage width) is only 19 feet.


In summary, loading/reloading an aircraft is a serious operation requiring a dozen people to do quickly and efficiently. Putting those dozen people, and their equipment, and all the ordinance into a mothership, getting the fighter to safely approach that mothership and touch down on top of it, then getting the crew into position to remove expended hardpoint pylons and reload new ones, then getting the plane to safely get back off the mothership... It's just not gonna happen with any current technology.

There was a proposed design for a twin-fuselage C-5 as a shuttle transport aircraft; the idea was that this aircraft could be used instead of the risky crane system to pick the shuttle off the ground at an alternate shuttle landing site like Edwards AFB:



An aircraft of this scale might, might, be able to support an aircraft coming in between the tails, docking, then using remote arms to load ordinance. This aircraft would, by wingspan, be the largest plane ever to fly, and would compete closely with the An-225 on every other size stat except total length.