Manually amending a DoE experiment suggested by JMP

[#1]

If for whatever reason, it is not possible to run a particular run, but a related one is possible, can the DoE design be manually amended? For example, if experiment ++-++ is suggested but is not possible and ++--+ is (and the latter does not appear elsewhere in the original design) can the user manually make the substitution, whilst bearing in mind that this change will likely alter the significance of the results generated?

[#2]

Yes. When you create a design in JMP...it's just a JMP data table that can be modified manually. The change may or may not alter the 'significance' whatever you mean by that word...but may change which terms are estimable in the model.

[#3]

Difficult to generalize with so little information. As Pete suggests, you can modify designs created by JMP, but this can impact resolution of the design (e.g., what terms can be estimated and which are confounded).  Why is that combination not possible?  Are your levels appropriate?  Should some terms be nested?

I'm not sure what you mean by "significance of results"?