Calculated Date of service with multiple rehire dates

Hi , I am try to find out the difference in multiple dates of rehire up to six times.

I have a start and end date , rehire date, The issues I have is try to subtract the date difference or length service & calculation must include 30 day calender every month and com
=DATEDIF(E3,B4+((E4-D4)+(E3-D3)),"md")&" Days, "&DATEDIF(E3,E3+((E4-D4)+(E3-D3)),"ym") &" Months , "&DATEDIF(E3,E3+((E4-D4)+(E3-D3)),"y")&" Years"

B4 : rehire date
E3: start date
D3: seperation date

I also have to minus three dates to come up with a new rehire date. please hep

HI , I am attaching the spreadsheet thanks for your help.

I am try to minus the the two length of service dates an return the information years , month and days. Then I need to add that to the rehired date to get the new prosposed date.

Date : Rehire Date Prospo Date Start Date Seperation Date SDATE Length of service
4/22/2013 4/21/2017 8/10/2016 8/10/2011 8/9/2012 30 Days, 11 Months, 0 Years 30 Days, 11 Months, 0 Years
4/22/2013 4/21/2017 4/13/2018 9/15/2012 12/31/2012 17 Days, 3 Months, 0 Years 16 Days, 3 Months, 0 Years


example:

30 Days, 11 Months, 0 Years
17 Days, 3 Months, 0 Years
______________________________

17 Days, 3 Months , 1 Years
- 4/21/2017

Then prospo date should be
04/24/2015


Thanks in advance

Rehire Date Prosponed Date Start Date Seperation Date Segment Total Length
10/14/2013 10/13/2017 8/10/2016 6/5/2010 8/31/2010 27 Days, 2 Months, 0 Years 27 Days, 2 Months, 0 Years
10/13/2017 7/8/2017 9/10/2012 12/14/2012 5 Days, 3 Months, 0 Years 5 Days, 3 Months, 0 Years
10/13/2017 6/3/2017 4/22/2013 8/30/2013 9 Days, 4 Months, 0 Years 9 Days, 4 Months, 0 Years
SUM: 9 Months 41 Days 0 Years 9 Months 41 Days 0 Years Time Served 11 Days, 10 Months , 0 Years


subtract rehire date from sum of length of service to come up with a new rehire date .

It is multiple rehire dates .I am try to minus ( B5) from M6 ( 9 months and 41 days 0 To get a new hire date. I also try to get M4 and M5 to display by every 30 days.