There should be a VA rating on each unit that would help.
Using the 30 amps of each unit we can come up with something general.
30 times 240 equal 7200. 7200 times 2 equals 14,400
14,400 subtract 12,000 equals 2,400
Now increase the demand found in column “C” by 5% for each KW or fraction thereof
8,000 times 115% equals 9,200 divided by 240 equals 38.33
210.19 says that a fifty amp circuit can be tapped as you propose so it looks as though what you propose would be code compliant. Always remember that anything less than code compliant is not safe.