Based on prior knowledge, we can analyze the relationship between the BMI feature and the task of determining whether a person has diabetes or not.

Typically, higher BMI values are associated with an increased risk of developing diabetes. Therefore, we can expect that individuals with higher BMI values are more likely to have diabetes.

To create the dictionary, we will consider typical BMI values for each target class ('yes' and 'no').

```json
{
    "yes": [32.5, 35.0, 38.7, 40.2, 42.9],
    "no": [20.1, 22.6, 24.9, 27.4, 29.8]
}
```

In this example, the BMI values provided are just for demonstration purposes. The actual values should be determined based on the specific dataset and the relationship between BMI and diabetes.