What is the systemic approach?
Families as cohesive systems Every person is part of a family and bonded by ties of birth to the family's mutual fate. These ties remain, even if your parents are unknown to you, or if you have been raised outside your family of birth. As individuals, we are not as free as we would sometimes like to believe.
Families are systems in which certain basic forces are extremely powerful. The operational forces that have been observed in family systems are: bonding, order, and a balance of giving and taking. Each (family)system strives towards balance in response to these forces.

Right to belong Every member of a system has an equal right to belong to the system. If someone has been excluded, forgotten or not respected, another member of the family will restore the balance by identifying with this person. At the purely unconscious level of the 'soul', he or she will take on the fate and behaviour of the excluded person.

Orders of love In each system, certain orders seem to be operating which need to be respected in order to keep the environment a healthy and loving one for its members . If the balance has been disrupted by some difficult fate, (e.g. a mother who is severely ill or has died at an early age) the system may react by changing the position of some family members in order to insure survival (e.g. an eldest daughter may move into a mother position). In this way, the 'natural' order is disturbed and entanglements may result.

First things first One of the unwritten laws of systems seems to be that what happens first in time takes precedence over that what happens later. (i.e., a couple relationship takes precedence over being a parent, parents take precedence over their children, the oldest child takes precedence over the next ones, etc.).
When this order is disturbed, it may indicate an entanglement due to an earlier event or some difficult fate in the family.
For the other 'orders' which have been observed in families, we refer to the literature.

Literature "Love's Hidden Symmetry" by Bert Hellinger, Hunter Beaumont en Gunthard Weber. ISBN 1-891944-00-2.
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Bert Hellinger