You can place a manual bet to circumvent this.
If you a greening up a back bet with a lay bet:
back, Price: r_ticks(bm_layp, X), Amount: (lay_payout - back_payout)/r_ticks(bm_layp, X)
If you a greening up a lay bet with a back bet:
lay, Price: r_ticks(bm_backp, -X), Amount: (back_payout - lay_payout)/r_ticks(bm_backp, -X)
Where X is the number of ticks of profit.