Crystal Reports Linking 1 to many to 1

Message

     I am having a problem linking my tables correctly.

Basiclly there is one table with information-Service call table).

There is a second table linked to the first by service call ID. 

This table has tasks that have been assigned to the serivce call. There can be one or many tasks. Each task has the same Equipment ID assigned to it.

A thrid table contains Equipment Information. It is linked to the second table by Equipment ID as the first table does not have the equipment ID.

There is a forth table that contains costs which is linked to the first table by Service call ID.

If I then do a grouping based on Equipment ID in the Equipment information table  the costs from the last table are duplicated based on the number of tasks in table 2. 

Is there any way to fix this in the linking? 