You need to create multiple properties corresponding the allowed Schema. The Semantic Property for all allowed schemas should be same. It should look something like this.
[SemanticProperty("Schema_Field")]
public List<SchemaModelA> A{ get; set; }
[SemanticProperty("Schema_Field")]
public List<SchemaModelB> B{ get; set; }
[SemanticProperty("Schema_Field")]
public List<SchemaModelC> C{ get; set; }