To truly grasp the material and find the "answers" within your own skill set, follow these steps:

If there are four children, use a 4-handshape. Point to the thumb (or index finger, depending on the dialect) for the oldest and work your way down.

Set up one person on your non-dominant side and the other on your dominant side.

Film yourself answering the prompts in the workbook. Compare your facial expressions to the DVD/Video models. In ASL, your face provides the grammar. Conclusion

Are they step-siblings? Half-siblings? Unit 4.14 introduces the "K" handshape twist for "step" and the "1/2" fraction sign.

Use your non-dominant hand to represent the total number of siblings.