set access-rule command works just fine with adding additional objects, I don't think that writing a script should be too complicated if you have experience with this.
Just for syntax reference, I used the following:
mgmt_cli set access-rule layer "Network" -r true rule-number 1 dst.add Host1
mgmt_cli set access-rule layer "Network" -r true rule-number 1 dst.add Host2
This added dst to a rule and the second added the second host without subtracting the first one, means this command should be suitable for you.
Kind regards, Amir Senn