It requires it own circuit. It can not be shared with anything else. That is in the NEC.

Now if it direct wired or plug in you are suppose to use a GFCI protection. Since some plug in you do NOT want to have a GFCI receptacle. Because if power ever goes out or if it trips you have to pull out the DW. So to avoid all issues use a GFCI circuit breaker. They cost abt the same as the receptacle. Also another thing is YOU CAN NOT SLAVE THE DW OFF OF ANOTHER RECEPTACLE OR GFCI

This is all NEC code. You should actually check with your local municipality on codes and amendments to them.

Since you say you are hardwiring  your DW you MUST use a GFCI circuit breaker. And the only thing allowed to be on it is the DW.

It s not safe or practical to share that circuit. There are reason for codes. It not just to protect the equipment but to protect you.

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If you insist on doing it the way your thinking. What you need to do is remove that receptacle you are not using. And replace with a blank coverplate. And use that receptacle box that you just removed and splice there.

2 things are temporary solved. That would be the safest most practical way to do it. And swap that breaker out for a GFCI breaker. It solves all the questiions.

Yes you can  however will the outlets ever be used while the DW  is In use?If your sure that adding in the dishwasher to the existing circuit won't cause overloading then yeah you can do that  However New N.E.C. requirements or code .Does require  GFCI protection for the dishwasher . Even if it's a older home that was not equiped with such devices By using either ab GFCI or  AFCI BREAKERS . I'm  not saying you have to install those expensive breakers or a GFCI PLUG OR COMBINATION AFCI/GFCI PLUG I am merely pointing out what the 2020 NEC requirements are Overall if your certain the circuit won't be over loaded , and you know what your talking into You can connect to the existing  circuit . If your hard wiring it directly , and with a whip of flexible conduit that will attach directly to the DW and the j box then your good If you use Romex or NM WIRE . STOP RIGHT THERE AND CALL A ELECTRICIAN. MC CABLE AND ROMEX ARE NOT TO BE USED  putting a 3 pronged cord is acceptable  if you use a gfci plug put it in a accessable location If not ( which is the old school way and is still acceptable in some cases  but never in new construction which will require a gfci or combo afci /gfci plug or breaker in the panel  )

Go ahead and hook it up I just wanted you to be aware of what the new code cycle has added about DW electrical requirements . Just be sure not to overload the circuit , and be sure you HAVE GROUNDED THE CONNECTION PROPERLY  if you have any doubts on how to ground the DW PROPERLY STOP AND CALL A ELECTRICIAN IF YOU HAVE ANY DOUBTS ON WHAT YOU NEED TO DO TO PROPERLY CONNECT THE DW STOP then call  electrician GROUNDING IS CRITICAL FOR YOUR SAFETY .depending on how old your house is There may not be a ground wire or EQUIPMRNT GROUND in your electrical system and lastly UG YOUR HOME ONLY HAS 2 PRONG OUTLETS WITH NO LOWER CENTER HOLE ( picture a face using the 2 slots for the plug as eyes the center hole I am talking about as the mouth .if your plugs have eyes only kind of like this -  | i   If your plugs look like the two lines and there is no other opening just two slots DO NOT HOOK YOUR DW to anything in your house and call a electrician DO NOT ATTEMPT RO HOOK IT UP .those systems have no ground and you can leave you and your family in a shocking situation .if your house has three pronged plugs THROUGH  OUT YOUR HOME your good to go and  equipment ground should be in the j box your connecting to .On a newer system using mine metallic j boxs you will connect directly to the bare ground wire inside the astic j box If you have steel j box's and still only have 2 wires still on a system using 3 pronged plugs you can safely connect the DW GROUND directly to the metal box interior using a green coated ground screw I IF NONE  OF WHAT IVE SAID HERE MAKES SENSE B,OR YOUR CONFUSED IR NOT SURE ABOUT YOUR ELECTRICAL PANELS GROUNDING ,AND BASICALLY IF IM TALKING GREEK TO YOU .....CALL A LOCAL LICENSED ELECTRICIAN AND DO  CONNECT THE DW YOURSELF safety first if you have any doubt about ANYTHING IVE MENTIONED ABOVE STOP AND CALLA LICENSED PRO people forget electricity is a indiscriminate killer that can be silent ,had no smell ,you can't see it BUT YOU CAN FEEL IT IF YOUR NOT CAREFUL AND KNOWLEDGEABLE UN HOW TO SAFELY HANDLE IT AND EVEN HOW TO PROPERLY AND SAFELY CONNECT THE WIRES There is a right and a wrong way to do this ,and just cause it will work does not mean it's safe especially if it's connected wrong .YES IT CAN.STILL WORK IF ITS CONNECTED WRONG the grounding is very important and older homes that used 2 prong outlets are a big deal when it comes to properly connecting equipment that had to be grounded for your SAFETY So making it work is one thing MAKING IT WORK PROPERLY ANF SAFELY IS CRITICAL TO YOU AND YOUR  FAMILYS SAFETY  So connecting it properly is super important DO NOT SCAB IT IN A SYSTEM WITHOUT PROPER GROUNDING 

did you check the power requirements of the dishwasher?  it's in the specs.  Note that when it starts, it probably draws slightly more than stated.