# More inclusive predecessor and successor domain for complex projects
**URL:** https://discuss.tryton.org/t/more-inclusive-predecessor-and-successor-domain-for-complex-projects/5409
**Category:** Ideas
**Tags:** project
**Created:** [July 4, 2022, 10:28am UTC](https://discuss.tryton.org/t/more-inclusive-predecessor-and-successor-domain-for-complex-projects/5409 "2022-07-04T10:28:43Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@cman](https://discuss.tryton.org/u/cman)
#### Post date: [July 4, 2022, 10:28am UTC](https://discuss.tryton.org/t/more-inclusive-predecessor-and-successor-domain-for-complex-projects/5409/1 "2022-07-04T10:28:43Z")
For simple projects, the built-in sequence works fine to order tasks, but for more complex projects, using the `project_plan` module seems like a logical way to go. But in that module, the `successor` and `predecessor` domain of siblings (currently implemented as `('parent', '=', Eval('parent', -1)`) is just too limiting to be useful.
I propose that a predecessor or successor could be any work within a single project tree (i.e. has a common ancestor in the same project). This should include any sub-projects (but probably should not descend into tasks within the sub-projects).
This would give the flexibility to organize a project tree around one logic and plan the project around another.
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### Author:  [@ced](https://discuss.tryton.org/u/ced)
#### Post date: [July 8, 2022, 10:19am UTC](https://discuss.tryton.org/t/more-inclusive-predecessor-and-successor-domain-for-complex-projects/5409/2 "2022-07-08T10:19:04Z")
I think it will make the project\_plan code much more complicated and this will prevent to build a correct [PERT](https://en.wikipedia.org/wiki/Program_evaluation_and_review_technique) graph.
If you have this need I guess your tree structure is not correct.