Help Required With Both Of These Clues...

[ZebuSanctuary]

Clue: 'sending an invoice for exchanging caresses?' Answer: 'Billing' Clue: They may be held by the checkers Answer: 'Reins' Thanks in advance

[novalis]

Billing and cooing - an old expression for kissing and cuddling.
To hold the reins means to keep things in check so the rein-holders are checkers.

[Buenchico]

1. Double meaning. ('Billing', as in 'billing and cooing', meaning to display affection).

2. One uses reins to 'check' a horse.

[ZebuSanctuary]

@Buenchico... Your explanation is worthy too of best answer. However I've awarded it to novalis on their speed in submitting the answers.