There are two ways to do this that come to mind:
You could create a node template for nodes of type property and use an Entity Field Query in a manner roughly following this pseudo-code:
$park = $node->field_park['value'];
$query = new EntityFieldQuery();
$result = $query->execute();
This will load a list the NIDs of all nodes that have field_park matching the value of $node->field_park['value'] (or wherever the node object stores your actual field value). To get more info than just the NID, you will want to do some kind of
foreach($result) that does a
node_load($nid) on each NID returned by the EFQ.
Option two is no-code: you could create a View and embed it on your node with something like Insert View. You would create the view with the following steps:
- Add a contextual filter that takes the node ID. This is so you can pass it a value so you get a view specific to each node you want it to appear on. Exactly how to do this is out of the scope of this question.
- Add a field for the node title. You can remove this later but it will keep you from getting confused while making the view. Give it a label if you want, make it grouping field number one, and exclude it from the view.
- Add a relationship. Choose "Entity Reference" for the relationship type, and then select "entity that is referenced via field_park" or whatever your node reference field is called.
- Add another content: title field. Under relationship, choose the relationship you just created. Set it to group by that field, create a label called "park:", and set it to exclude from display.
- Add another relationship. Choose type "Entity Reference" and this time choose "referencing entity": "entity that is referencing Content via field_park"
- Add another field for node: title and this time select the relationship you just created. Give it a label like, "sister property:" if you want.
Violá. Now you have a view that will allow you to pass an NID and will tell you the title of that property, its park, and all sister properties.