Is there a way I can use a Master with sub-projects on different calendars?

Question

Wondering if I can get some advice creating a Master Project (MSP2013 Standard, no Project Server software). I have 3 projects of which 2 are utilising a Standard calendar 8:00AM to 5:00PM 8hr day 40hr week, and 1 project (the largest) utilising a Customised
calendar 7:30AM to 3:30PM  7.5hr day 37.5hr week.
The dominant project is running on the Customised calendar so I have set the Global Options in the Master to reflect the 7:30AM to 3:30PM  7.5hr day 37.5hr week. Then set the calendar in Master Project Information default to the Customised calendar. 
Finally, the resource pool for all 3 projects is in the Master.
No problem when I insert the sub-project into the Master which is using the customised calendar. All data is reflective of the original project.  However, when I insert either of the 2 sub-projects using the 40hr week calendar the Summary Headings for
the inserted projects are incorrect.  For example, instead of being 2 weeks duration, the summary heading displays 2.13 weeks, and instead of 4 weeks duration, the summary heading displays 4.27 weeks.
The Global settings appear to be interfering with the projects on the Standard calendars.  I am surprised and extremely frustrated as I thought the settings in the Master would not affect anything?
Sorry guys, have posted this in 3 different places as it is so important to me!

Answer 1

Hi Guys, many thanks for your responses, really appreciate your time, however I am finding this much more complex. I have put my original sheets to one side and started again. Once again this is very important hence a lot of detail here. I am hoping something
will provide a clue where I am going wrong.
New sheet |save as Master | Change Working Times |copy Standard Calendar and called it 37.5 Hour
Calendar| No exceptions | Work Weeks tab |Details | Set Monday to Friday 7:30AM to 12:30PM then 1:00PM to 3:30PM. Selected Options | Schedule | Start 7:30AM End 3:30PM |Hours 7.5 | Hours per week 37.5 |Auto Scheduled |Duration Hours|
Work Hours |Fixed Duration | OK OK. Project | Project Information | Calendar changed to 37.5 Hour Calendar | Save.
In my previous example I noted that my main project is scheduled 37.5 hours but I will skip inserting it here, the issue is subprojects with different settings to the Global, that is mixing projects with different calendars in a Master.
New sheet | save as 40 Hour Project |Change Working Times |Standard Calendar | No exceptions | Selected Options | Schedule | Start 8:00AM End 5:00PM |Hours 8 Hours per week 40 |Auto Scheduled |Duration Weeks | Work Hours |Fixed Duration
| OK OK | Save.
Entered 5 new Tasks, all 2weeks duration, all linked Finish to Start. Inserted a Summary Heading named 40 Hour Summary | 40 Hour Summary Duration = 10 wks | Start 9 June 1014 8:00 AM | Finish 15 August 2014 5:00 PM |Created 1 Resource called Fred | 100%
|$100 Standard Rate | Assigned Fred to all tasks 100% | Project | Project Information | Statistics | 10w 400h $40.000 |Save and Close | All correct.
Back to the Master | Project | Insert Subproject | selected 40 Hour Project |Duration 400 hrs | Start 9 June 2014 8:00AM | Finish 21 August 2014 10:30AM. It appears the Global settings are affecting the inserted subproject note the finish time is now
10:30AM. Project | Project Information |Statistics |Duration 400h | Work 400h | All correct!
BUT | select View Outline Show Subtasks |This is where further changes have happened | Project | Project Information |Statistics |Duration is now
374.5h | Work 400h.
Besides information being displayed incorrectly these figures will affect all Reports. This example suggests you cannot have subprojects in a Master that are associated with different calendars? Surely not! Please help if you can, I have
spent hours searching for answers, and I can’t believe I am the only one who has come across this! Many thanks.......