The thing about Poser is there's as many ways to do something as there are people doling it. Let's try this the "All inside Poser way" with minimal import-export steps. This technique is fine for personal use. A pro content developer will use some extra steps for improved quality.

1) In a new, empty scene import the OBJ for the Figure you want to convert from LaFemme1 to LaFemme2. When you import make sure you un-check all the import options. You don't need any "fixing" of the imported OBJ. (This is the only import step. The rest of this is pure Poser)

2) From the content library in the Props category load the "LF1 to LF2 Prefit Tool"

3) Select the Clothes and from the Top Menu choose Object > Copy Morphs From ...

4) Pick the prefit tool "LF1-LF2 Prefit" as the source of the morphs

5) Make sure the Clothes are still selected. Find the new morphs "LF2 Shape" and dial it to 1.0

6) You're done with the LF1-LF2 Prefit tool. Delete it from your scene.

7) Save often, save your sanity. Save with a new file name.

Now you have clothing geometry that's morphed to the shape of LF2 but it's not a figure. Next we need to turn a simple geometry into a Poser figure. This is the "All Poser" way. When you get comfortable with this work flow this is the point where you can touch up the auto-generated shape to be more artistic. That's for another day.

8) Load the figure or the "DEV" figure that's the target. In this case use "LF2 DEVSuitHigh"

9) your scene should look like the Clothes are on the Dev figure. There may be some small poke through. This is when you'd fix those by editing the morph that you created earlier. For now let's just get figure finished.

10) Save for your sanity. You will almost certainly need to return to this point.

11) Switch to the Fitting room This is where the Clothes become a figure.

12) [New] fitting session

13) Pick the Object, That will be the shorts prop that you added the morph to. Un-check the option to zero the prop. You need that morph you created and dialed in earlier.

14) Pick the Goal. That's the figure it's going to fit. That will be the LF2 DEV SuitHigh.

15) [OK]

16) [Create Figure] ... Give the new shorts a name "CFLaFemme-Shorts_LF2" will do for now. [OK]

17) Uncheck all the body parts, then add back only the parts that this clothing needs.

18) Uncheck Transfer Morphs, (We'll transfer morphs later) Uncheck Auto Group, Check Zero rotations

19) [OK] (And it looks like nothing happened ... )

20) Switch back to the Pose Room. (Still looks like nothing happened ...)

21) The new figure the fitting room made and the prop you made at the beginning are right on top of each other.

22) Save for your sanity

23) select the PROP shorts "CFLaFemme-Shorts 1" Delete them from the scene.

24) You should have the newly created shorts figure and LF2 DEV Suit in your scene.

25) Now we need to make the newly created shorts figure better.

26) Select the Shorts figure you created "CFLaFemme-Shorts_FL2"

27) Top Menu > Figure Copy Joint Zones From ...  Pick "LF2_DEVSuit" as the source for the joint zones.

28) Top Menu > Copy Morphs From ...  Pick "LF2_DEVSuit" as the source for the Morphs.

29) (Optional) Un-check irrelevant morphs (Arm morphs don't apply to a pair of shorts) Uncheck the "TOOL FaFemme Shape"

30) [Ok] (This may take a while.)

31) Select the Clothes' BODY and make sure it's setup to conform properly.

32) With the shorts selected choose a library folder in the Figures category where you want to save the new LF2 fitting shorts.

33) If you're asked where to save the OBJ let Poser save it in the Geometries folder (Default choice)

You now have a pair of shorts that fit LaFemme 2.

Next to explore is adding more morphs so the shorts will fit other characters. Maybe tomorrow.