Enabling status change for the preceding activity

hello all,

we are working on CRM 5.0 & are trying to reflect changes in the status field of an activity transaction on the basis of the value in the status field of its follow up activity.

For eg. if the status field of the follow up activity is set to 'complete', the status filed of the preceding activity should also change to 'complete'.

Is there some BAdI to do this. Please guide me in this regard.

thank you

deepanshu