The foldover design we discussed in class can be analyzed sequentially
in Minitab.  Recall that Minitab's foldover command doesn't augment 
the design matrix in the current worksheet but generates the entire 
foldover design in a new worksheet--your old responses will have to 
be re-entered in the new worksheet.

The shot put example was run using the default design for 7 factors
in 8 runs so we didn't have to specify the design generators.  After
analyzing this initial screening design, a foldover was needed to decide
whether 3 main effects were active or two main effects and their
interaction was active.  To generate the foldover design, we selected 
DOE>Create Factorial Design (as usual), specified 7 factors and then 
chose the 1/16 fraction (8 runs) under Design.

Under Design, we selected Fold Design>Fold on all factors, deselected
Randomize Runs and used the default (principal) fraction.  A new
worksheet (separate from the earlier analysis) is created and all the
responses need to be re-entered.  Analysis is similar to analysis of 
fractional factorial designs though a Block effect, measuring any
systemic difference between the two runs in the foldover, is also
tested.

Another approach

Minitab has another approach that doesn't require the data to be 
reentered.  After generating the initial design, you can select
DOE>Modify Design...Select Fold Design, then click OK (do not
click on Put Modified Design in a New Worksheet, since that would 
defeat the purpose of this shortcut).  The additional runs will have
been added to the end of your worksheet--you now need to add the
responses from the follow-up experiment.  When analyzing this design,
it seems that only the terms from the initial experiment may be
included; you'll have to select the Terms box in Analyze Design...
and click the >> to include the terms from the foldover experiment.